Method of interdigitating flowable material with bone tissue

ABSTRACT

A method and system of interdigitating flowable material with spinal tissue is disclosed which in one embodiment, includes forming a structure that may partially surround a portion of the spinal material and introducing flowable material into the portion of spinal tissue surrounded by the structure.

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 11/464,793, now U.S. Pat. No. 7,666,227 and acontinuation-in-part of U.S. patent application Ser. No. 11/464,815, nowU.S. Pat. No. 7,670,375 both of which were filed on Aug. 15, 2006, andclaim the benefit of U.S. Provisional Application No. 60/708,691, filedAug. 16, 2005, U.S. Provisional Application No. 60/738,432, filed Nov.21, 2005 and U.S. Provisional Application No. 60/784,185, filed Mar. 21,2006, all of the above are incorporated herein by reference. In additionto claiming the benefit of the filing dates of all of the above regularand provisional applications, the present application also claims thebenefit of U.S. Provisional Patent Application No. 61/030,287, filedFeb. 21, 2008, which is incorporated herein by reference. The presentapplication also hereby incorporates herein by reference U.S. patentapplication Ser. Nos. 11/464,782; 11/464,790; 11/464,807; and11/464,812, all of which were filed on Aug. 15, 2006.

FIELD OF THE INVENTION

The present subject matter generally relates to apparatus and methodsfor interdigitating flowable material with spinal tissue.

BACKGROUND OF THE INVENTION

A variety of physical conditions involve two tissue surfaces that, fordiagnosis or treatment of the condition, need to be separated ordistracted from one another and then supported in a spaced-apartrelationship. Such separation or distraction may be to gain exposure toselected tissue structures, to apply a therapeutic pressure to selectedtissues, to return or reposition tissue structures to a more normal ororiginal anatomic position or form, to deliver a drug or growth factor,to alter, influence or deter further growth of select tissues or tocarry out other diagnostic or therapeutic procedures. Depending on thecondition being treated, the tissue surfaces may be opposed orcontiguous and may be bone, skin, soft tissue, or a combination thereof.

One such a condition that occurs in the orthopedic field is vertebralcompression fractures. Vertebral compression fractures affect asignificant part of the population and add significant cost to thehealth care system. A vertebral compression fracture is a crushing orcollapsing injury to one or more vertebrae. Vertebral fractures aregenerally but not exclusively associated with osteoporosis, metastasis,and/or trauma. Osteoporosis reduces bone density, thereby weakeningbones and predisposing them to fracture. The osteoporosis-weakenedvertebrae can collapse during normal activity and are also morevulnerable to injury from shock or other forces acting on the spine. Insevere cases of osteoporosis, actions as simple as bending forward canbe enough to cause a vertebral compression fracture. Vertebralcompression fractures are the most common type of osteoporotic fracturesaccording to the National Institute of Health.

The mechanism of such vertebral fractures is typically one of flexionwith axial compression where even minor events can cause damage to theweakened bone. While the fractures may heal without intervention, thecrushed bone may fail to heal adequately. Moreover, if the bones areallowed to heal on their own, the spine may be deformed to the extentthe vertebrae were compressed by the fracture. Spinal deformity may leadto breathing and gastrointestinal complications, and adverse loading ofadjacent vertebrae.

Vertebral fractures happen most frequently at the thoracolumbarjunction, with a relatively normal distribution of fractures around thispoint. Vertebral fractures can permanently alter the shape and strengthof the spine. Commonly, they cause loss of height and a humped back.This disorder (called kyphosis or “dowager's hump”) is an exaggerationof the spinal curve that causes the shoulders to slump forward and thetop of the back to look enlarged and humped. In severe cases, the body'scenter of mass is moved further away from the spine resulting inincreased bending moment on the spine and increased loading ofindividual vertebrae.

Another contributing factor to vertebral fractures is metastaticdisease. When cancer cells spread to the spine, the cancer may causedestruction of part of the vertebra, weakening and predisposing the boneto fracture.

Osteoporosis and metastatic disease are common root causes leading tovertebral fractures, but trauma to healthy vertebrae can also causefractures ranging from minor to severe. Such trauma may result from afall, a forceful jump, a car accident, or any event that compresses orotherwise stresses the spine past its breaking point. The resultingfractures typically are compression fractures or burst fractures.

Vertebral fractures can occur without pain. However, they often cause asevere “band-like” pain that radiates from the spine around both sidesof the body. It is commonly believed that the source of acute pain incompression fractures is the result of instability at the fracture site,allowing motion that irritates nerves in and around the vertebrae.

Until recently, treatment of vertebral compression fractures hasconsisted of conservative measures including rest, analgesics, dietary,and medical regimens to restore bone density or prevent further boneloss, avoidance of injury, and bracing. Unfortunately, the typicalpatient is an elderly person. As a class of patients, the elderlygenerally do not tolerate extended bed rest well. As a result, minimallyinvasive surgical methods for treating vertebral compression fractureshave recently been introduced and are gaining popularity.

One technique used to treat vertebral compression fractures is injectionof bone filler into the fractured vertebral body. This procedure iscommonly referred to as percutaneous vertebroplasty. Vertebroplastyinvolves injecting bone filler (for example, bone cement, allographmaterial or autograph material) into the collapsed vertebra to stabilizeand strengthen the crushed bone.

In vertebroplasty, physicians typically use one of two surgicalapproaches to access thoracic and lumbar vertebral bodies:transpedicular or extrapedicular. The transpedicular approach involvesthe placement of a needle or wire through the pedicle into the vertebralbody, and the physician may choose to use either a unilateral access orbilateral transpedicular approach. The extrapedicular technique involvesan entry point through the posterolateral corner of the vertebral body.

Regardless of the surgical approach, the physician generally places asmall diameter guide wire or needle along the path intended for the bonefiller delivery needle. The guide wire is advanced into the vertebralbody under fluoroscopic guidance to the delivery point within thevertebra. The access channel into the vertebra may be enlarged toaccommodate a delivery tube. In some cases, the delivery tube is placeddirectly into the vertebral body and forms its own opening. In othercases, an access cannula is placed over the guide wire and advanced intothe vertebral body. After placement, the cannula is replaced with thedelivery tube, which is passed over the guide wire. In both cases, ahollow needle or similar tube is placed through the delivery tube intothe vertebral body and used to deliver the bone filler into thevertebra.

In this procedure, the use of lower viscosity bone filler and higherinjection pressures tend to disperse the bone filler throughout thevertebral body. However, such procedures dramatically increase the riskof bone filler extravasation from the vertebral body. The transpedicularapproach requires use of a relatively small needle (generally 11 gaugeor smaller). In general, the small diameter needle required for atranspedicular approach necessitates injecting the bone filler in a moreliquid (less viscous) state and/or at a relatively high pressure. Thedifficulty of controlling or stopping bone filler flow intoinjury-sensitive areas increases as the required pressure increases.

In contrast to the transpedicular approach, the extrapedicular approachmay accommodate a larger needle (up to about 6 mm internal diameter inthe lumbar region and lower thoracic regions). The larger needle used inthe extrapedicular approach allows injection of bone filler in athicker, more controllable viscous state and/or at a lower pressure.Therefore, many physicians now advocate the extrapedicular approach sothat the bone filler may be delivered through a larger cannula underlower pressure. However, the transpedicular approach is still thepreferred approach. In either approach, caution, however, must still betaken to prevent extravasation, with the greatest attention given topreventing posterior extravasation because it may cause spinal cordtrauma. Physicians typically use repeated fluoroscopic imaging tomonitor bone filler propagation and to avoid flow into areas of criticalconcern. If a foraminal leak results, the patient may require surgicaldecompression and/or suffer paralysis.

Another type of treatment for vertebral fractures is known asKyphoplasty. Kyphoplasty is a modified vertebral fracture treatment thatuses one or two balloons, similar to angioplasty balloons, to attempt toreduce the fracture and, perhaps, restore some vertebral height prior toinjecting the bone filler. One or two balloons are typically introducedinto the vertebra via bilateral transpedicular cannula. The balloons areinflated to reduce the fracture. After the balloon(s) are deflated andremoved, leaving a relatively empty cavity, bone cement is injected intothe vertebra. In theory, inflation of the balloons may restore somevertebral height. However, in practice it is difficult to consistentlyattain meaningful and predictable height restoration. The inconsistentresults may be due, in part, to the manner in which the balloon expandsin a compressible media, such as the cancellous tissue within thevertebrae, and the structural orientation of the trabecular bone withinthe vertebra, although there may be additional factors as well.

Thus there is a need for devices and methods to treat the abovementioned diseases, in particular compression vertebral fractures.

Another condition that can be treated by distraction or separation oftissue layers is disruption or degeneration of an intervertebral disk.An intervertebral disk is made up of strong connective tissue whichholds one vertebra to the next and acts as a cushion between vertebras.The disk is divided into two distinct regions: the nucleus pulposus andthe annulus fibrosus. The nucleus lies at the center of the disk and issurrounded and contained by the annulus. The annulus contains collagenfibers that form concentric lamellae that surround the nucleus. Thecollagen fibers insert into the endplates of the adjacent vertebralbodies to form a reinforced structure. Cartilaginous endplates arelocated at the interface between the disk and the adjacent vertebralbodies.

Proper disk height is necessary to ensure proper functionality of theintervertebral disk and spinal column. The disk serves severalfunctions, although its primary function is to facilitate mobility ofthe spine. In addition, the disk provides for load bearing, loadtransfer and shock absorption between vertebral levels. The weight ofthe person generates a compressive load on the disks, but this load isnot uniform during typical bending movements. During forward flexion,the posterior annular fibers are stretched while the anterior fibers arecompressed. In addition, a translocation of the nucleus occurs as thecenter of gravity of the nucleus shifts away from the center and towardsthe extended side.

Changes in disk height can have both local and broader effects. On thelocal (or cellular) level, decreased disk height results in increasedpressure in the nucleus, which can lead to a decrease in cell matrixsynthesis and an increase in cell necrosis and apoptosis. In addition,increases in intra-diskal pressure create an unfavorable environment forfluid transfer into the disk, which can cause a further decrease in diskheight.

Decreased disk height may also result in significant changes in theoverall mechanical stability of the spine. With decreasing height of thedisk, the facet joints bear increasing loads and may undergo hypertrophyand degeneration, and may even act as a source of pain over time.Increased stiffness of the spinal column and decreased range of motionresulting from loss of disk height can lead to further instability ofthe spine, as well as back pain. Radicular pain may result from adecrease in foraminal volume caused by decreased disk height.Specifically, as disk height decreases, the volume of the foraminalcanal, through which the spinal nerve roots pass, decreases. Thisdecrease may lead to spinal nerve impingement, with associated radiatingpain and dysfunction.

Finally, adjacent segment loading increases as the disk height decreasesat a given level. The disks that must bear additional loading aresusceptible to accelerated degeneration and compromise, which mayeventually propagate along the destabilized spinal column.

In spite of all of these detriments that accompany decreases in diskheight, where the change in disk height is gradual many of the illeffects may be “tolerable” to the spine and may allow time for thespinal system to adapt to the gradual changes. However, a suddendecrease in disk volume caused by herniation which requires surgicalremoval of the disk or disk nucleus can heighten the local and globalproblems noted above.

The many causes of disruption or degeneration of the intervertebral diskcan be generally categorized as mechanical, genetic and biochemical.Mechanical damage can include herniation in which a portion of thenucleus pulposus projects through a fissure or tear in the annulusfibrosus. Genetic and biochemical causes can result in changes in theextracellular matrix pattern of the disk and a decrease in biosynthesisof extracellular matrix components by the cells of the disk.Degeneration is a progressive process that usually begins with adecrease in the ability of the extracellular matrix in the centralnucleus pulposus to bind water due to reduced proteoglycan content. Witha loss of water content, the nucleus becomes desiccated resulting in adecrease in internal disk hydraulic pressure that ultimately results ina loss of disk height. This loss of disk height can cause non-tensileloading and buckling of the annulus. The loss of disk height also causesthe annular lamellae to delaminate, resulting in annular fissures andrupture of the annulus. Herniation may then occur as rupture leads toprotrusion of the nucleus.

Many disk defects are treated through a surgical procedure, such as adiskectomy in which the nucleus pulposus material is removed. During atotal diskectomy, a substantial amount (and usually all) of the volumeof the nucleus pulposus is removed and immediate loss of disk height andvolume can result. Even with a partial diskectomy, loss of disk heightcan ensue.

Diskectomy alone is the most common spinal surgical treatment. Theprocedure is frequently used to treat radicular pain resulting fromnerve impingement by a disk bulge or disk fragments contacting thespinal neural structures.

In another common spinal procedure, the diskectomy may be followed by animplant procedure in which a prosthesis is introduced into the cavityleft in the disk space after the nucleus material is removed. Thus far,the most prominent prosthesis is a mechanical device or a “cage” that issized to restore the proper disk height and is configured for fixationbetween adjacent vertebrae. These mechanical solutions take on a varietyof forms including solid kidney-shaped implants, hollow blocks filledwith bone growth material, and threaded cylindrical cages.

A challenge of inserting a disk implant posteriorly is that a devicelarge enough to contact the endplates and slightly expand theintervertebral space between the endplates must be inserted through alimited space. This challenge is often further heightened by thepresence of posterior osteophytes, which may cause converging or “fishmouthing” of the posterior endplates that results in very limited accessto the disk. A further challenge in degenerative disk spaces is thetendency of the disk space to assume a lenticular shape, which requiresa relatively larger implant that often is not easily introduced withoutcausing trauma to the nerve roots. The size of rigid devices that maysafely be introduced into the disk space is thereby limited.

Cages of the prior art have been generally successful in promotingfusion and approximating proper disk height. Cages inserted from theposterior approach, however, are limited in size by the interval betweenthe nerve roots. Some examples of prior art devices are shown in U.S.Pat. No. 5,015,247 to Michelson, which describes an artificial threadedspinal fusion implant; U.S. patent application Ser. No. 10/999,727 toFoley et al., which describes vertebral spacer devices for repairingdamaged vertebral disks; U.S. Pat. No. 4,309,777 to Patil, whichdescribes a motion preserving implant that has spiked outer surfaces toresist dislocation and contains a series of springs to urge thevertebrae away from each other; and finally, U.S. patent applicationSer. No. 10/968,425 to Enayati, which describes an expandableintervertebral prosthesis. All the above patents and patent applicationsare hereby incorporated herein by reference.

Therefore, a need remains for a device that can be inserted into anintervertebral disk space in a minimally invasive procedure and is largeenough to contact and separate adjacent vertebral endplates. There alsoremains a need for a device that reduces potential trauma to the nerveroots and still allows restoration of disk space height.

Another related area in which tissue distraction may be required isspinal fusion. Fusion is a surgical technique in which one or more ofthe vertebrae of the spine are united together (“fused”) so that motionno longer occurs between them. In spinal fusion surgery, bone grafts areplaced around the spine, and the body then heals the grafts over severalmonths—similar to healing a fracture—and joins or “fuses” the vertebraetogether.

There are many potential reasons for a surgeon to consider fusingvertebrae, such as treatment of fractured (broken) vertebra, correctionof deformity (spinal curves or slippages), elimination of pain frompainful motion, treatment of instability, and treatment of some cervicaldisk herniations.

One of the more common reasons to conduct spinal fusion is to treat avertebral fracture. Although not all spinal fractures need surgery, somefractures, particularly those associated with spinal cord or nerveinjury, generally require fusion as part of the surgical treatment.Certain types of spinal deformity, such as scoliosis, also are commonlytreated with spinal fusion. Scoliosis is an “S” shaped curvature of thespine that sometimes occurs in children and adolescents. Fusion can beused as a form of treatment for very large curves or for progressivelyworsening smaller curves. Additionally, fusion can be used to treatspondylolisthesis, which is a condition that occurs when hairlinefractures allow vertebrae to slip forward on top of each other.

Another condition that is treated by fusion surgery is actual orpotential instability. Instability refers to abnormal or excessivemotion between two or more vertebrae. It is commonly believed thatinstability can either be a source of back or neck pain or causepotential irritation or damage to adjacent nerves. Although there issome disagreement on the precise definition of instability, manysurgeons agree that definite instability of one or more segments of thespine can be treated by fusion.

Cervical disk herniations that require surgery usually need removal ofthe herniated disk (diskectomy) and fusion. With this procedure, thedisk is removed through an incision in the front of the neck(anteriorly) and a small piece of bone is inserted in place of the disk.Although disk removal is commonly combined with fusion in the neck, thisis not generally true in the low back (lumbar spine).

Spinal fusion is also sometimes considered in the treatment of a painfulspinal condition without clear instability. A major obstacle to thesuccessful treatment of spine pain by fusion is the difficulty inaccurately identifying the source of a patient's pain. The theory isthat pain can originate from painful spinal motion, and fusing thevertebrae together to eliminate the motion will eliminate the pain.

There are many surgical approaches and methods to fuse the spine thatinvolve placement of a bone graft between the vertebrae. The spine maybe approached and the graft placed either from the back (posteriorapproach), from the front (anterior approach) or by a combination ofboth. In the neck, the anterior approach is more common and in thelumbar and thoracic regions a posterior approach is usually employed.

The ultimate goal of fusion is to obtain a solid union between two ormore vertebrae. Fusion may or may not involve the use of supplementalhardware (instrumentation), such as plates, rods, screws and cages.Instrumentation can sometimes be used to correct a deformity, but itusually is just used as an internal splint to hold the vertebraetogether while the bone grafts heal. Whether or not hardware is used,bone or bone substitutes are commonly used to induce the vertebrae tofuse together. The bone may be taken either from another bone in thepatient (autograft) or from a bone bank (allograft).

Yet another related area in which tissue distraction may be required isin the replacement of essentially an entire or a partially removedvertebra. Such removal is generally necessitated by extensive vertebralfractures, or tumors, and is not usually associated with the treatmentof disk disease. Vertebral bodies may be compromised due to disease,defect, or injury. In certain cases, it becomes necessary to remove orreplace one or more of the vertebral bodies or disks to alleviate painor regain spinal functionality.

In the treatment of a removed vertebra, a device may be used to form atemporary structural mechanical support that aids in replacing theremoved vertebra with bone filler, such as calcium phosphate whichpromotes healing. A number of methods and devices have been disclosed inthe prior art for replacing a diseased or damaged vertebral body. Theseprior art devices and the procedures associated therewith havedifficulty in maintaining the proper structural scaffolding while acastable material, such as bone cement, is hardened in the cavity leftby the removed vertebral body. The maintaining of proper structuralscaffolding has been especially difficult in a minimally invasiveposterior surgical approaches.

Spinal fusion or lumbar spinal fusion is one way to treat a compromisedvertebral body due to unstable burst fractures, severe compressionfractures, and tumor decompression. In a spinal fusion procedure, thedisks above and below the compromised vertebral body are removed and astrut graft and plate are then used to make the vertebrae above andbelow the replaced vertebral body grow together and become one bone.

Some of the prior art vertebral body replacement systems include U.S.Pat. No. 6,086,613 to Camino et al., which describes an interbody fusionsystem made of a titanium mesh and endplates; U.S. Pat. No. 5,192,327 toBrantigan, which describes the use of singular or stackable modularimplants; U.S. Pat. No. 6,585,770 to White et al., which describes ahollow body with an opening to receive bone growth inducing material;and U.S. Pat. No. 6,758,862 to Berry, which describes a vertebralreplacement body device. All of the aforementioned references are herebyincorporated herein by reference.

Thus, there remains a need for improved devices for replacing one ormore removed or partially removed vertebral bodies especially from aposterior approach and in a minimally invasive surgical intervention.

SUMMARY OF INVENTION

The present subject matter generally relates to methods and apparatusfor interdigitating flowable material with spinal tissue, and moreparticularly, to interdigitating flowable material with spinal bonetissue of a vertebral body, forming an amalgam or mixture of bone tissueand flowable material.

One aspect of the present subject matter is directed to a method ofinterdigitating flowable material with spinal tissue. The methodincludes forming a barrier that at least partially surrounds at least aportion of spinal tissue and interdigitating flowable material with theportion spinal tissue surrounded by or located within the barrier.

Another aspect of the present subject matter is directed to a method oftreating spinal bone tissue. The method comprises inserting a generallyelongated member into spinal bone tissue and changing the configurationof the elongated member to form a structure that at least partiallysurrounds at least a portion of the spinal bone tissue. In oneembodiment, the structure completely encircles the portion of the spinalbone tissue. After the structure has been formed, flowable material isintroduced into the surrounded portion of the spinal bone tissue tointerdigitate the flowable material with the portion of spinal bonetissue.

Yet a further aspect of the present subject matter is directed to amethod of treating spinal bone tissue. The method includes guiding anelongated member into spinal tissue. The elongated is then formed into astructure that at least partially surrounds at least a portion of thespinal bone tissue. In one embodiment, the structure completelyencircles the portion of spinal bone tissue. After the structure hasbeen formed, flowable material is deployed into the portion of thespinal bone tissue surrounded by or within the structure.

BRIEF DESCRIPTION OF THE FIGURES

In the course of this description, reference will be made to theaccompanying drawings, wherein:

FIG. 1 is a partial side view of a normal human vertebral column;

FIG. 2 is comparable to FIG. 1, but shows a vertebral compressionfracture in one of the vertebral bodies;

FIG. 3 is a top view of a vertebra with an endplate partially removed;

FIG. 4 is a side view of the vertebra of FIG. 3;

FIG. 5 is a perspective view of one embodiment of the distraction deviceof the present invention, shown in the form of a coil or a spring;

FIG. 6 is a vertical cross-sectional view of the distraction device ofFIG. 5;

FIG. 7 is a perspective view of one embodiment of a delivery system ofthe present invention, showing a cannula, pusher and a pre-deployeddistraction device;

FIG. 8 is a perspective view of the delivery system of FIG. 7 showingthe distraction device partially ejected from the cannula;

FIGS. 9-11 are partial side views of the system of FIG. 7, illustratinga deployment sequence of the distraction device;

FIG. 12 is a top cross-sectional view of a vertebra and the deploymentsystem of FIG. 7, showing the deployment of a distraction device withinthe vertebral body;

FIG. 13 is a side cross-sectional view of the vertebra and deploymentsystem of FIG. 12, illustrating the partial deployment of thedistraction device within a fractured vertebra;

FIG. 14 is a side cross-sectional view of the vertebra and deploymentsystem of FIG. 12, with the distraction device essentially fullydeployed to restore the height of the vertebral body;

FIG. 15 is a top cross-sectional view of a vertebra having a distractiondevice located within the vertebral body and bone filler (or “cement”)being delivered within the vertebral body;

FIG. 15A is a top cross-sectional view of a vertebra having adistraction device located within the vertebra body, the distractiondevice having channels or grooves to direct the flow of injected bonefiller;

FIGS. 16-26 are perspective views of different embodiments ofdistraction devices with different cross-sectional profiles;

FIG. 26A is an illustration of a prior art device in which a “cage” isinserted between adjacent vertebrae;

FIG. 26B is a top cross-sectional view of an intervertebral disk shownwith a disk removal tool inserted into the disk for disk nucleus pulpousremoval;

FIG. 26C is a side partial cross-sectional view of the intervertebraldisk of FIG. 26B shown between superior and inferior vertebrae and witha distraction device being delivered into the intervertebral disk via acannula;

FIG. 26D is a partial cross-sectional anterior view of theintervertebral disk of FIG. 26B shown between superior and inferiorvertebrae and with the distraction device completely deployed within thedisk;

FIG. 26E is an illustration of a prior art device in which a “cage” isused for vertebral body replacement;

FIG. 26F is an illustration of another prior art device used forvertebral body replacement;

FIG. 26G is a top cross-sectional view of a vertebra shown with avertebral bone removal inserted into the vertebra for vertebral bodybone removal;

FIG. 26H is a side view of the vertebra of FIG. 26G shown within asection of a vertebral column and having portions broken away to showthe delivery of a distraction device into the space created by removalof vertebral body bone;

FIG. 26I is a side view of the vertebra of FIG. 26G shown within asection of a vertebral column and having portions broken away to showthe distraction device completely deployed within the vertebral body;

FIG. 26J is a side view of a section of a vertebral column in which thevertebral body of one of the vertebra along with the adjacent disks havebeen substantially removed and a distraction device is being deployedinto the space created by such removal;

FIG. 26K is a side view of the vertebral column section of FIG. 26Jshown with the distraction device completely deployed;

FIG. 27 is a partial cross-sectional side view of another embodiment ofa distraction device and delivery system employing a pusher foradvancing the distraction device over a guide wire;

FIG. 28 is a partial cross-sectional side view of the distraction devicedelivery system of FIG. 27, with the pusher advanced distally and thedistraction device partially advanced over a coiled section of the guidewire;

FIG. 29 is a partial cross-sectional side view of the distraction devicedelivery system of FIG. 27, with the distraction device substantiallyadvanced over the coiled section of the guide wire;

FIG. 30 is a perspective view of a vertebra with the superior endplateremoved to show the delivery of a guide wire into the vertebral body;

FIG. 31 is a perspective view of the vertebra shown in FIG. 30 with theguide wire partially deployed within the vertebral body;

FIG. 32 is a perspective view of the vertebra of FIG. 30 shown after thecannula and introducer sheath have been removed and a distraction deviceand pusher mounted on the guide wire;

FIG. 33 is a perspective view of the vertebra of FIG. 30 shown with thedistraction device partially advanced or deployed within the vertebralbody;

FIG. 34 is a perspective view of the vertebra of FIG. 30 shown with thedistraction device substantially fully deployed within the vertebralbody;

FIG. 35 is a side cross-sectional view of the vertebra of FIG. 30, withthe distraction device fully deployed within the vertebral body;

FIG. 36 is a top cross-sectional view of a vertebra having a distractiondevice deployed within the vertebral body and bone filler being injectedinto the treatment site within the distraction device;

FIG. 37 is a top cross-sectional view of the vertebra shown in FIG. 36having bone filler injected and contained within the inner space definedby the distraction device when in the deployed position defining agenerally hollow cylindrical coil or helical shaped support structurewithin the vertebra;

FIG. 38 is a perspective view of the vertebra shown in FIG. 36 havingbone filler substantially occupying the area within the distractiondevice;

FIGS. 38A-38G further illustrate one exemplary method of interdigitatingflowable material with bone tissue of the vertebra to form an amalgam ofbone tissue and flowable material in accordance with the present subjectmatter;

FIGS. 39-48 are perspective views of different embodiments ofdistraction devices, showing a variety of shapes and cross-sectionalprofiles including profiles that all allow the distraction device tobend or curve;

FIG. 48A is one embodiment of a distraction device element;

FIG. 48B is a partial cross-sectional side view of one embodiment of adistraction device having multiple distraction device elements slidablymounted on a guide wire;

FIG. 49 is a top partial cross-sectional view of a vertebral body withtwo delivery access opening being used in a trans-pendicular approachfor side by side placement of distraction devices or guide wires;

FIG. 50 is a perspective view of one embodiment of the delivery systemof the present invention for placing two distraction devices or guidewires in a relative superior and inferior position;

FIG. 51 is a side cross-sectional view of a vertebral body incombination with the system of FIG. 50 at least partially deployed;

FIG. 52 is a perspective view of another embodiment of the deliverysystem of the present invention having a double distraction device orguide wire configuration in a relative lateral position;

FIG. 53 is a top partial cross-sectional view of a vertebral body andthe system of FIG. 52 at least partially deployed;

FIG. 54 is a perspective view of yet another embodiment of the system ofthe present invention having a quadruple distraction device or guidewire configuration in relative superior and inferior lateral positions;

FIG. 55 is a side view of a wheel driven delivery apparatus in astarting position;

FIG. 56 is a side view of the wheel driven delivery apparatus of FIG. 55during deployment of the distraction device;

FIG. 57 is a perspective view of a spool type delivery system duringdeployment;

FIG. 58 is a side view of a ratchet delivery apparatus;

FIG. 58A is a side view of a ratchet delivery apparatus in which thedistraction device or guide wire exits out of the side of the distal tipof the delivery apparatus;

FIG. 59 is a side view of a vertebral column shown with a disk nucleusremoval tool entering one of the intervertebral disk from a posteriorapproach;

FIG. 60 is a cross-sectional view of the spinal region illustrating inexample of an anterior approach which can be used for deployment of adistraction device;

FIG. 61 is a top cross-sectional view of an intervertebral disk shownwith a disk removal tool inserted into the disk for disk nucleus pulpousremoval;

FIG. 62 is a top cross-sectional view of the intervertebral disk of FIG.61 shown after the nucleus pulpous of the disk has been removed;

FIG. 63 is a top cross-sectional view of the intervertebral disk of FIG.61 shown with a cannula inserted into the disk and a guide wirepartially deployed within the nucleus space;

FIG. 63A is a side partial cross-sectional view of the intervertebraldisk of FIG. 61 shown between superior and inferior vertebrae and withthe guide wire partially deployed;

FIG. 64 is a top cross-sectional view of the intervertebral disk of FIG.61 shown with the guide wire deployed within the nucleus disk space andthe cannula removed;

FIG. 65 is a top cross-sectional view of the intervertebral disk of FIG.61 shown with a distraction device placed over the guide wire partiallydeployed within the nucleus space;

FIG. 65A is a side partial cross-sectional view of the intervertebraldisk of FIG. 61 shown between superior and inferior vertebrae and withthe distraction device mounted on the guide wire and partially deployedwithin the intervertebral disk;

FIG. 66 is a top cross-sectional view of the intervertebral disk of FIG.61 shown with a distraction device defining a support structureddeployed within the nucleus space;

FIG. 67 is a top cross-sectional view of an intervertebral disk shownwith a cannula inserted into the nucleus space and a guide wirepartially deployed into the nucleus space;

FIG. 68 is a top cross-sectional view of the intervertebral disk of FIG.67 shown after the cannula has been removed and a distraction devicepartially deployed within the nucleus space;

FIG. 69 is a top cross-sectional view of the intervertebral disk of FIG.67 shown with a second cannula inserted into the nucleus space and asecond guide wire deployed into the nucleus space;

FIG. 70 is a top cross-sectional view of the intervertebral disk of FIG.67 shown with a second distraction device placed over a delivery trackand partially deployed within a nucleus space;

FIG. 71 is a top cross-sectional view of the intervertebral disk of FIG.67 shown with two distraction devices deployed within a nucleus space;

FIG. 72 is a side view of a vertebral column with adjacent vertebraehaving non-parallel endplates;

FIG. 72A is a schematic illustration of a distraction device deliverysystem inserted into an intervertebral disk using a posterior approach;

FIG. 72B is a side partial cross-sectional view of the vertebral columnof FIG. 72 shown with the distraction device illustrated in FIGS. 73 and74 partially deployed within an intervertebral disk of the vertebralcolumn;

FIG. 73 is a perspective view of another embodiment of a distractiondevice of the present invention;

FIG. 74 is a side view of the distraction device of FIG. 73 when coiledto define a support structure;

FIG. 75 is a top view of a cannula delivering a guide wire in a spiralconfiguration;

FIG. 76 is a top cross-sectional view of an intervertebral disk with theguide wire deployed into the nucleus space;

FIG. 77 is a top cross-sectional view of the intervertebral disk of FIG.76 with a distraction device placed over the guide wire and partiallydeployed within the vertebral body; and

FIG. 78 is a top cross-sectional view of the intervertebral disk of FIG.78 shown with the spiral shape distraction device deployed within thenucleus space;

FIG. 79 is a side view of a section of a vertebral column with portionsof a vertebral body broken away to show a guide wire deployed into thevertebral body via a cannula;

FIG. 80 is a side view of the vertebral column section of FIG. 79 withportions of the vertebral body broken away to show a distraction devicebeing deployed into the vertebral body via a guide wire;

FIG. 81 is a side view of the vertebral column section of FIG. 79 withportions of the vertebral body broken away to show the distractiondevice deployed within the vertebral body;

FIG. 82 is a side view of a section of a vertebral column in which thevertebral body of one of the vertebra along with the adjacent disks havebeen substantially removed, and a guide wire is being deployed into thespace created by such removal;

FIG. 83 is a side view of the vertebral column section of FIG. 82 shownwith a distraction device mounted on the guide wire and partiallydeployed into the space created by the removal of the vertebral body andadjacent disks;

FIG. 84 is a side view of the vertebral column section of FIG. 82 shownwith the distraction device fully deployed within the space created bythe removal of the vertebral body and disks.

DETAILED DESCRIPTION

FIG. 1 illustrates a section of a healthy vertebral (spinal) column,generally designated as 100, without injury. The vertebral column 100includes adjacent vertebrae 102, 102 a and 102 b and intervertebraldisks 104, 104 a, 104 b and 104 c separating adjacent vertebrae.

FIGS. 3 and 4 illustrate in more detail a normal vertebra and itsattributes. The vertebra, generally designated as 102, includes avertebral body 106 that is roughly cylindrically and comprised of innercancellous bone 108 surrounded by the cortical rim 110, which iscomprised of a thin layer of cortical compact bone. The cortical rim 110can be weakened by osteoporosis and may be fractured due to excessivemovement and/or loading. The body 106 of the vertebra is capped at thetop by a superior endplate 112 and at the bottom by an inferior endplate114, made of a cartilaginous layer. To the posterior (or rear) of thevertebral body 106 is the vertebral foramen 116, which contains thespinal cord (not shown). On either side of the vertebral foramen 116 arethe pedicles 118, 118 a, which lead to the spinal process 120. Otherelements of the vertebra include the transverse process 122, thesuperior articular process 124 and the inferior articular process 126.

FIG. 2 illustrates a damaged vertebral column, generally designated as128, with a vertebral body 130 of a vertebra 132 suffering from acompression fracture 134. The vertebral body 130 suffering from thecompression fraction 134 becomes typically wedge shaped and reduces theheight of both the vertebra 132 and vertebral column 128 on the anterior(or front) side. As a result, this reduction of height can affect thenormal curvature of the vertebral column 128. It is understood that paincaused by a compressed vertebral fracture 134 can sometimes be relievedby procedures like vertebroplasty and kyphoplasty, (these procedureshave been described in the background), however such procedures havesafety concerns and sometimes fails to provide a desired or predictableheight restoration.

Turning now to a detailed description of illustrated embodiments of thepresent invention. The apparatus or device of the present invention,which is generally defined as a distraction device, can serve toactively separate tissue layers by engaging them and forcing them apart,or to support the separation of tissue layers separated by thedistraction device itself or by other devices or processes or acombination of these. Accordingly, the term “distracting device” isintended to have a general meaning and is not limited to devices thatonly actively separate tissue layers, only support tissue layers or onlyboth actively separate and support tissue layers. For example, thedistraction device in general can be used to actively separate layers oftissue and then be removed after such separation, or the distractiondevice could be used to support layers of tissue that have beenpreviously separated by a different device. Alternatively, thedistraction device can be used to actively separate the layers of tissueand remain in place to support the layers of tissue in order to maintainsuch separation. Unless more specifically set forth in the claims, asused herein, “distraction device” encompasses any and all of these.

It should also be understood that various embodiments of the device,system and method of the present invention are illustrated for purposesof explanation in the treatment of vertebral compression fractures,height restoration of a diseased disk, vertebral fusion proceduresand/or replacement of removed disks or vertebra. However, in its broaderaspects, the present invention is not limited to these particularapplications and may be used in connection with other tissue layers,such as soft tissue layers, although it has particular utility andbenefit in treatment of vertebral conditions.

FIG. 5 illustrates one embodiment of a distraction device, generallydesignated as 136, in accordance with the present invention. In thisembodiment, the distraction device 136 is preferably comprised of anelongated member, such as thread or ribbon, made of a shape memorymaterial, such as a Nitinol (NiTi) or other suitable alloy (Cu—Al—Ni,Ti—Nb—Al, Au—Cd, etc.), a shape memory polymer or other suitablematerials. In this illustrated embodiment, the distraction device threador ribbon has a rectangular cross-section. However, as described in moredetail below, the distraction device can have a variety of shapes andprofiles.

When deployed between tissue layers, as shown in FIGS. 5, 14, 16-26, 29,35, 39-48, 50-54, 65, 71, 74, 72, 81 and 84, for example, thedistraction device 136 defines a support structure of a predeterminedconfiguration such as a multi-tiered arrangement, scaffolding orplatform that serves to actively separate or support (or both) opposedtissue layers. In FIG. 5, the distraction device, as deployed, has ahelical, coil or spring-like configuration. As illustrated, thedistraction device defines a helical configuration with a tight pitchforming an essentially hollow cylinder or cage. As shown, each turn orwinding 140 is wound on top of the previous winding 140 a to form aplurality of stacked windings or tiers with little or no spacing betweeneach winding or tier. In this configuration, the distraction device 136forms a very stiff column or support structure 141 along the axis of acenter line of the coil or spring as shown in FIG. 6.

Preferably, the support structure 141 includes or defines an innerspaceor resident volume 145. As used herein, “resident volume” refersgenerally to a structural characteristic of the support structure. Theresident volume is a volume that is generally defined by the distractiondevice, when it is in the deployed configuration. The resident volume isnot necessarily a volume completely enclosed by the distraction deviceand can be any volume generally defined by the distraction device. Thisterm does not necessarily mean that the resident volume is an open orvoid volume or cavity and does not preclude a situation in which theresident volume is, at some point in time, filled with another material,such as bone filler, cement, therapeutic drugs or the like. It also doesnot preclude the resident volume from containing undisturbed humantissue that is located or remains within the resident volume during orafter deployment of the distraction device, as will be explained in moredetail below. For example, if the distraction device is employed toseparate adjoining soft tissue layers, such as subcutaneous fat andunderlying muscle tissue, the resident volume of the distraction devicemay be hollow or void of tissue after separation. On the other hand, ifinserted into a vertebra having cancellous bone tissue therein, theresident volume will contain undisturbed bone tissue and no void orcavity is formed by the distraction device.

In order to shape the distraction device 136 like a coil or spring, itis helpful to understand the characteristics of a shape memory alloy.Nickel-Titanium alloys, such as Nitinol, exhibit the phenomena ofthermal shape memory and superelasticity. The term thermal shape memoryrefers to the material's ability to return from a plastically deformedshape to a pre-determined shape upon increasing the temperature of thematerial. The term superelasticity refers to the elastic ability of thematerial. Materials with superelastic characteristics can be deformed byapplying a force to constrain the material in a deformed or constrainedshape. Once the force or constraint is removed, the material willsubstantially return to its pre-determined or initial shape.Superelastic materials, such as Nickel-titanium alloys, can beconsiderably more elastic than stainless steel. The pre-determined orinitial shape can be referred to as the free state and the deformedshape can be referred to as the constrained state.

The initial or pre-determined shape of a shape memory material isnormally set by a heat treatment process, which is well known in theart. In the present invention, the material selected is wound on amandrel and securely attached so it can be heat treated to set thedesire shape, in this case, to be configured like a tight pitch coil orhelical shape. The heat cycle is typically around 500° C. and for aperiod of 10 minutes to 60 minutes depending on the strength of thematerial, spring constant and oxide layer required. The mandrel couldrange in sizes from about 0.125 to about 2.0 inches, but is preferablyaround 0.5 inches in diameter. The wind direction could be right hand orleft hand, with a tight pitch, having little or no space betweenadjacent coils or turns. However, other pitches could be used ifrequired by the application, and if the material is of sufficientstrength, the coils can be spaced apart.

Because of the shape memory characteristics of the material used in theconstruction of the distraction device 136, the distraction device canbe deformed prior to or during delivery to a desired treatment site, andthen returned to its original shape within the treatment site. In otherwords, the distraction device has an inherent tendency or is predisposedto form itself into its deployed shape. Referring to FIGS. 5-8, forexample, the distraction device 136 is first formed into the helical orcoil shape seen in FIG. 5. It may then be unwound or deformed into asubstantially linear configuration or pre-deployed configuration (seeFIG. 7) by insertion into a cannula 142 for delivery. The cannula 142constrains the distraction device 136 (shown in phantom within thecannula) in the deformed (straight) shape as the distraction device ispassed through the cannula. While constrained within the cannula, thedeformed shape or pre-deployed shape of the elongated member issubstantially linear in that the shape can be perfectly straight or theshape could include slight bends or zigzags. Upon exiting an opening 144in a distal end portion 146 of the cannula 142, the distraction device136, by change of configuration, returns to its initial or free state,as illustrated in FIG. 8. As shown, a coiled portion of the distractiondevice 136 is outside of the cannula 142 in the free state and theremaining portion of the distraction device is inside the cannula in aconstrained state. When the distraction device 136 exits the cannula 142and reforms into a coil shape it defines or provides a support structure141 that includes a resident volume 145. The support structure 141 maybe used in a vertebra to actively separate endplates and restore height,or the support structure may be used to support endplates that have beenpreviously separated by a different device.

The cannula 142 preferably has a lumen 143 and a bore 144 that iscomplementary to or the same as the cross-section of the distractiondevice 136. The distraction device 136 can be pushed or pulled throughthe cannula 142 with the aid of a pushrod 150 or other suitableadvancement device. The proximal end 152 of the cannula 142 may have aknob or handle 154 or other structure for ease of use and a proximal end156 of the pushrod 150 also may have a knob or handle 158 as well.

FIGS. 9, 10 and 11 depict the action of the distraction device 136 as itreforms into its initial or deployed configuration upon being advancedout of the distal end 146 of the cannula 142. As previously explained,the distraction device 136, i.e., the elongated member or ribbon, isinserted or loaded into the cannula 142 where it may be deformed into aconstrained state, e.g., a substantially straight or linear state. Thepushrod 150 (not shown) or other suitable advancement mechanism ismanipulated to advance the distraction device out of the distal end 146of the cannula 142. As the distraction device 136 exits out the distalend portion 146 of the cannula 142 in the direction of the arrow A, thedevice begins to return to its wound or coil shape because it is nolonger being constrained by the cannula. In the illustrated embodiment,the distraction device 136 returns to the initial configuration as itwinds in a clockwise direction as indicated by arrow B.

As shown in FIG. 10, the distraction device 136 continues to advance outof the distal end 146 of the cannula 142, in the direction of arrow Aand continues to wind in the direction of arrow B. As the number ofwindings 140 increase, the height or extent of the coiled shaped supportstructure 141 also increases as represented by arrow C. Preferably, inuse, the extent or height of the support structure will increase in thedirection of tissue separation. The process will continue until thedesired height or extent of the support structure 141 is obtained and/orthe distraction device 136 is fully displaced from the cannula. When thedistraction device is completely pushed out of the cannula 142, asillustrated in FIG. 11, the coil shaped support structure 141 is at itsfull deployed height, which preferably is the distance required forheight restoration of a compressed vertebra or a diseased disk when thedevice is used for such treatments.

In a typical procedure for treatment of a vertebral compressionfracture, access to the vertebra can be gained by using the sameprocedures and techniques that are used for the other vertebralprocedures mentioned above, or by any other procedures and techniquesgenerally known by those skilled in the art. Referring to FIGS. 12 and13, which illustrate one potential procedure, an access opening 160 isdrilled into the cortical rim 110 of the vertebral body 130 of avertebra 132 suffering from a compression fracture 134. The cannula 142is inserted through the access hole 160 into the vertebral body 130.Alternatively, the cannula 142 may be placed adjacent to the access hole160 instead of inserted through the access hole. Typically, the accessopening 160 will be drilled through the pedicle 118, which is sometimesreferred to as a transpedicular approach. However, the access hole 160could be made in any other portion of the cortical rim 110 as thephysician may chose.

The distraction device 136 may be prepositioned within the cannula 142,which constrains the distraction device in the deformed or pre-deployedconfiguration. As the pushrod 150 is advanced, the distraction device136 is advanced out of the distal end portion 146 of the cannula 142 andinto the cancellous bone 108 of the vertebral body 130. Upon exiting thecannula 142, the distraction device 136 will begin to revert, by changeof configuration, to its initial or deployed coil shape to definesupport structure 141. Thus, as it is advanced from the cannula, thedistraction device 136 winds up into the relatively spongy cancellousbone 108 of the vertebral body 130 as shown in FIG. 13. Preferably, asthe distraction device traverses or passes through the cancellous bone108 there is no compression of cancellous bone. Additionally, in apreferred embodiment, the distraction device does not create asignificant void or cavity within the cancellous bone, but instead windsthrough the cancellous bone so that undisturbed cancellous bone 108 a islocated within the resident volume 145 defined by the support structure141.

As deployment of the distraction device 136 progresses into thecancellous bone 108 between the endplates 112, 114, in this embodiment,the spring-shaped distraction device support structure 141 will contactthe endplates and start to distract the endplates (or actively separatethem) apart from each other as the support structure increases inheight. The distraction device 136 will be advanced out of the cannula142 until the distraction device attains the desired height or extent asmeasured in the direction of endplate separation, or the endplates 112,114 have been separated by a desired distance. Typically, thedistraction device 136 is advanced until the height of the distractiondevice support structure 141 is such that it returns the endplates 112,114 to a normal pre-compression position, or such other spacing as thephysician deems appropriate as illustrated in FIG. 14, thereforealleviating a potential deformity that could eventually result inkyphosis. It is understood that the action accomplished by thedistraction device preferably restores all or a substantial portion ofthe original height of the vertebra, although there may be circumstanceswhere partial height restoration is deemed sufficient.

In one embodiment of the present invention, the height of the vertebrais estimated prior to the procedure by measuring adjacent vertebrae, andthen an appropriate sized distraction device that will achieve thedesired height upon completely exiting the cannula is selected.Alternatively, the height of the distraction device could be monitoredduring the procedure, and when the desired height is attained, thedistraction device (“ribbon”) could be severed at a location near thedistal end of the cannula.

Another optional and beneficial aspect of the distraction device of thepresent invention is the ability to control the delivery of flowablematerial, such as bone filler, for example bone cement, allograph,autograph or some other biocompatible material, or therapeutic drug intothe treatment site. One example of an appropriate bone filler ispolymethyl methacrylate (PMMA), commercially available as Kyphx HV-Rfrom Kyphon, Spineplex from Stryker, Simplex from Stryker Howmedica andParallax Acrylic Resin with Tracers TA from Arthocare. The distractiondevice also can be used to control the delivery of drugs or other agentsor fluids, depending on the application.

For example, once the support structure 141 defined by the distractiondevice is in place, bone filler 162 can be introduced into the treatmentsite to assist in stabilization of the distraction device and to aid insupporting the separation of the endplates 112, 114. As illustrated inFIG. 15, a syringe 164 can be used to deliver the bone filler 162 intothe treatment site. The tip 166 of the syringe 164 can be insertedbetween the windings 140, 140 a (shown in FIG. 14) of the coil shapeddistraction device 136 to access the resident volume 145 (which may ormay not contain undisturbed cancellous bone, depending on the desiredapplication) defined by the support structure 141. When the residentvolume 145 is filled with cancellous bone, introduction of bone fillerinto the resident volume creates a cancellous bone/bone filler amalgam,similar to prior vertebroplasty procedures, and the support structure141, in effect, acts like a container or barrier that contains the bonefiller 162 within a specified location and prevents or reduces thepotential for bone filler contact with more sensitive tissue such asnerve fibers. In alternative embodiments, the support structure may alsoserve to limit and direct the flow of the bone filler into areas outsidethe distraction device, as illustrated in FIG. 15A and explained in moredetail below. The container effect greatly reduces the complicationsassociated with injection of bone filler because the container-likeeffect of the distraction device greatly reduces the chances ofextravasation.

The distraction device can have a variety of the cross-sectionalprofiles configurations, as shown in FIGS. 16-26. However, it will beunderstood that other designs or profiles could be used based on theappropriate type of treatment required without departing for the presentinvention. Turning now to the illustrated configurations, thecross-sectional profile of the elongated member or ribbon of thedistraction device 136 may be of a variety of shapes, depending on theapplication and desired attributes. In certain applications, the profilemay be more significant to functionality than in other applications.

In FIG. 16, the cross-sectional shape of the distraction device isgenerally rectangular. When the distraction device is made from a shapememory material using the process described above, the winding surfaceon the mandrel is preferably the short axis for better stability andincreased surface contact when inserted into a vertebra. In other words,the distraction device is formed so that the wider side contacts thetissue to be distracted (e.g., endplates of a vertebra) to providereduced contact pressure. However, the distraction device could also bewound on the long axis depending on the application. The range of thematerial profile could be from about 0.005×0.010 inches (about 0.127mm×0.254 mm) (height×width) to about 0.10×0.50 inches (about 2.54mm×12.7 mm), but preferably in the range of 0.01×0.02 inches (about 12.7mm×0.5 mm) to 0.05×0.25 inches (about 1.27 mm×6.35 mm).

If desired, the distraction device 136 a can include lateral grooves orslots 170 or other lateral passageways at strategic locations. Thesegrooves 170 or other passageways may be formed by drilling, cutting,grinding or compressing the distraction device material. When thedistraction device is made of a shape memory material, the grooves orpassageways can be formed either before or after winding and heattreating. The grooves 170 can be uniformly or randomly spaced apart and,depending on the desired treatment, located only on one side of thesupport structure defined by the distraction device. The grooves 170 canbe used to direct and limit the flow of bone filler injected into andaround the treatment site. For example, as illustrated in FIG. 15A, thegrooves 170 can be located on the distraction device so that they are ononly the anterior side 172 of the support structure. When the grooves170 are arranged as such, the grooves control the direction of the bonefiller 162 so that the bone filler injected into the center area 145 adefined by the support structure 141 a is directed to flow toward theanterior portion 174 of the vertebral body and away from the posteriorportion 176 where the bone filler 162 could penetrate the blood venousreturn system, which could create embolism complications or cause spinalcord trauma.

In FIG. 17, the cross-sectional shape of the distraction device 136 b isthat of a generally rectangular tube having a channel 178 extendingtherethrough. This profile configuration may be similar to therectangular outer dimensions detailed in the previous embodiment and mayhave a wall 180 within the range of about 0.002 to 0.25 inches (about0.05 mm to 6.35 mm), but more preferably in the range of about 0.005 to0.020 inches (about 0.127 mm to 6.35 mm).

The distraction device could also include apertures or holes 182 whichextend through the wall 180 and communicate with the internal bore orchannel 178. The apertures 182 can be uniformly or randomly spaced apartand may be of the same size or vary in size. Additionally, the apertures182 could be limited to the inner wall of the distraction device or tothe outer wall of the distraction device or could be located on both theinner and outer walls. Further, the apertures 182 could be limited toone side of the distraction device, such as on the anterior side orposterior side. Bone filler can be delivered to the treatment site byinserting the tip of the syringe into the channel 178 and injecting thebone filler into the channel. The bone filler will flow along thechannel 178 and escape out of the apertures 182 in the desireddirections into the treatment site. The location and arrangement of theapertures will determine the direction of bone filler injected withinthe treatment site.

The distraction device also may be coated with a polymer based of bonefiller material that can be activated upon implantation and diffusedinto the surrounding tissue. This potential feature is applicable to adistraction device of any cross-sectional shape.

In FIG. 18, the cross-sectional shape is round. This profile may beslightly less stable during certain treatments because, in some cases,the windings could have the tendency to slip over each other. Howeverintroduction of bone filler material into the center of the windingsmay, after curing add substantially to the stability of this distractiondevice as well as the others shown in FIGS. 16-26. The diameter of thecircular cross-sectional distraction device in FIG. 18 preferably rangesfrom about 0.005 to 0.025 inches (about 0.127 mm to 0.635 mm).

In FIG. 19, the cross-sectional shape is square. This profile hassimilar advantages as the rectangular profile and would be much stifferat the same width dimension as the rectangular one.

In FIG. 20, the cross-sectional shape is double round. This profile hasimproved stability over a single round profile while being easy to wind.The double round profile could be extruded as such or welded together orotherwise joined prior to winding and heat treatment. The size of eachround section is preferably in the same range as the round profile.

In FIG. 21, the cross-sectional shape is that of a round tube thatincludes a channel or bore 184 that forms a lumen through thedistraction device. This profile may have similar dimensions as theround profile, and may have a wall 186 with a thickness in the range ofabout 0.002 to 0.05 inches (about 0.05 mm to 1.27 mm). This embodimentof the distraction device may also include apertures, generally similarto the apertures 182 described above with respect to FIG. 17, for flowof bone filler or other material into the treatment site.

In FIG. 22, the cross-sectional shape is oblong. This profile can beobtained by taking a distraction device that has the same dimensions asthe round profile and flattening it, preferably prior to heat treatmentif the device is made of a shape memory material. The flattening processcould use roller technology where the material is pushed between rollersthat are separated by a distance less than the diameter of thedistraction device. Several passes might be necessary depending on thethickness required. One of the advantages is potentially an increase instability over a round profile without having any sharp corners or edgesthat are commonly associated with interfering surfaces.

In FIG. 23, the cross-sectional shape is that of an oblong tube. Thisprofile is generally similar to the oblong profile, but includes acenter channel or bore 188 defining a lumen through the distractiondevice. Additionally, this embodiment could also include the aperturesgenerally similar to those described above with respect to FIG. 17.

In FIG. 24, the cross-sectional shape is a combination of the aboveshapes. This profile combines two or more of the previously describedprofiles. For instance, the device could have a square and a roundprofile, as shown. It is understood that any combination of profiles canbe achieved using one or more profiles as might be required by theapplication.

In FIG. 25, the cross-sectional shape is a custom profile. This type ofprofile may require special manufacturing process like special extrusiondies or secondary manufacturing after extrusion to create the desiredprofile. The advantage of such profile would be the lockingcharacteristic of the windings on top of each other to form a very solidcolumn not only in the vertical direction but also resistant to slidingor shifting in the lateral direction as well.

In FIG. 26, the cross-sectional shape is another custom profile havingbenefits as described above with reference to FIG. 25.

The distraction devices of the present invention may also be used inintervertebral disk treatments and intervertebral body fusionprocedures, as well as, total or partial vertebral body replacementsprocedures. One of the advantages of the present invention is theability to use the device in a minimally invasive surgery setting thatallows the surgeon to use an endoscopic approach to remove damagedspinal tissue due to disease, such as trauma or tumor and to deploy thedevice into the space created by such removal.

FIG. 26A illustrates a prior art device, sometimes referred to as a“cage,” that is used in intervertebral disk treatments andintervertebral body fusion procedures. These cage type devices typicallyhave a fixed size that does not substantially change before, during orafter implantation. Thus, in order to implant “cage” type devices, arelatively large incision is made in the patient's back and spinaltissue to accommodate the size of the device being inserted.Additionally, the use of a separate tool may be required to separate ordistract the spinal tissue prior to insertion of the device between thetissue.

In one minimally invasive method of an intervertebral disk treatment orintervertebral body fusion procedure in accordance with the presentinvention, a disk nucleus removal tool 190, such as rongeurs, curettes,probes or dissectors, is inserted through a small access hole 191 in theannulus fibrous 192 of an intervertebral disk 193, as illustrated inFIG. 26B. The removal tool 190 is used to remove a portion of or theentire disk nucleus pulpous 194 by endoscopic techniques and proceduresgenerally known to those skilled in the art.

Referring to FIG. 26C, a delivery cannula 142 is inserted through theaccess hole 190 and a distraction device 136 is deployed into the space195 created by the removal of the nucleus pulpous 194. As describedabove, the distraction device 136 preferably has a substantially linearpre-deployed configuration for deployment through the cannula 142 and acoiled or deployed configuration upon exiting the cannula in which thedistraction device defines a support structure 141. As the distractiondevice 136 exits the cannula, the support structure 141 increases inextent heightwise within the space 195. As deployment of the distractiondevice 136 progresses, the support structure 141 will cause theendplates 196 a and 196 b of adjacent vertebrae 102 a, 102 b,respectively, to distract or separate. The distraction device 136 willbe advanced out of the cannula 142 until the distraction device 136 hascompletely exited the cannula 142 or the support structure 141 hasattained the desired height. Typically, the distraction device 136 isadvanced out of the cannula until the height of the support structure141 is such that it returns the endplates 196 a, 196 b to a normalposition, as illustrated in FIG. 26D.

In a procedure in which the distraction device 136 is designed to beadvanced completely out of the cannula 142, the desired height of thesupport structure 141 is pre-determined and a distraction device of anappropriate size is chosen for use. In a procedure in which thedistraction device 136 is deployed until the desired height of thesupport structure 141 is attained, the height of the support structuremay be monitored under fluoroscopy, and once the support structure hasreached the desired height, the distraction device may be severed at alocation near the distal end portion of the cannula.

Upon deployment, the distraction device restores disk height andstabilizes the vertebral column. Depending on the amount of nucleuspulpous tissue removed and the deployment location of the supportstructure, the resident volume of the support structure may besubstantially empty or may contain some nucleus pulpous tissue.Optionally, bone filler, such as bone cement, allograph or autograph, orother therapeutic drugs may be inserted into the resident volume definedby the support structure and/or around the support structure to aid instabilization of the device and/or to promote bone fusion between theadjacent vertebrae.

FIGS. 26E and 26F illustrate prior art devices, also sometimes referredto as “cages,” that are used in vertebral body replacement (VBR)procedures. In a VBR procedure using such cage type devices, a portionof or the entire vertebral body is removed, and the cage is insertedinto the space of the removed vertebral body. Similar to the prior artcage described above, cages of the type illustrated in FIG. 26E have afixed size that does not substantially change before, during or afterdeployment. Thus, a relatively large incision is made in a patient'sback and spinal tissues to implant such a device. Additionally, theprocedure may require the use of a separate device to distract thetissue in order to accommodate insertion of the device.

The prior art device illustrated in FIG. 26F is somewhat different thanthat of the one shown in FIG. 26E in that it has individual sectionswhich are inserted to build the device or cage. Again these sections arerelatively large and require a relatively large incision forimplantation.

In one minimally invasive partial VBR procedure of the presentinvention, a vertebral bone removal tool 197 is inserted through a smallaccess hole 160 c of a vertebral body 130 c as illustrated in FIG. 26G.The vertebral bone removal tool 197 can be used to remove a portion ofthe vertebral body or completely remove the vertebral body usingendoscopic techniques and procedures generally known to those skilled inthe art. Typically, this procedure is use to remove damaged vertebralbone.

Referring to FIG. 26H, after the damaged cancellous bone 108 c has beenremoved, a delivery cannula 142 is inserted through the access hole 160c and a distraction device 136 is deployed into the vertebral body 130 cthrough the cannula, using similar procedures and techniques asdescribed above. As the distraction device 136 is deployed, it defines asupport structure 141 that separates and supports the endplates 112 c,114 c of the vertebral body 130 c, as illustrated in FIG. 26I. After thedistraction device 136 has been deployed, the resident volume of thesupport structure may be substantially empty or the resident volume maycontain some cancellous bone depending on the amount of cancellous boneinitially removed and the deployment location of the support structure.In any event, the distraction device itself does not compress thecancellous tissue to form a cavity or void volume. Optionally, bonefiller or therapeutic drugs may be inserted into the resident volumeand/or around the support structure to stabilize the support structureand/or to promote bone fusion.

In one minimally invasive method of a total VBR procedure, the vertebralbody removal tool described above is used to move substantially all of avertebral body, and optionally, a disk removal tool is used tosubstantially remove the adjacent disks. Referring to FIG. 26J, thedistal end portion 146 of a cannula 142 can be inserted into the space198 created by the removal of the vertebral body and/or adjacent disks,and a distraction device 136 can deploy into the space, using similarminimally invasive procedures and techniques described above. Uponexiting the cannula 142, the distraction device 136 forms a supportstructure 141 that increases in height as the distraction device isdeployed. As the support structure 141 increases in height, it contactsendplate 112 d of superior vertebra 130 d and endplate 114 d of inferiorvertebra 130 e to distract and support the vertebrae in a spaced-a-partrelation, as illustrated in FIG. 26K.

The deployed support structure 141 provides support and stabilizes thevertebra column. Optionally, bone filler or therapeutic drugs may beinserted into the resident volume and around the support structure tostabilize the support structure and/or to promote bone fusion.

FIG. 27 illustrates another embodiment of the distraction device anddelivery system of the present invention. In this embodiment, thedistraction device 202 is deployed with the aid of a guide wire ordelivery track 200. Prior to deployment, the distraction device 202preferably has an elongated generally linear shape and includes a centerbore or passageway (shown in FIG. 39-FIG. 48) for slidably mounting ontothe guide wire. The distraction device 202 should be sufficientlyflexible to follow along the contour of the guide wire 200 for example,the distraction device 202 may be required to take on a generallyelongated shape for mounting on a guide wire for deployment into thetreatment site and a generally coil or spring shape within the treatmentsite.

The distraction device 202 is preferably made from biocompatiblematerials that are suitable for long term implantation into human tissuein the treatment of degenerative tissue, trauma or metastatic conditionsor where a tissue distraction device is needed. The material used mayalso be a biological material such as, Calcium Phosphate, TricalicumPhosphate, Hydroxyapatite, or any other suitable biological material.The biocompatible materials may be PEEK (polyetheretherketone), Nylon,NiTi or any other suitable. The material may be solid or porous fortissue ingrowth, and may elute therapeutic or growth enhancing agents.One of the advantages of using biological or biocompatible material totreat vertebral compression fractures is that these elements have a morenatural like substance. However, other materials could be used and stillbe within the scope of the present invention.

The guide wire 200 includes a proximal end portion 204 and a distal endportion 206. The distal end portion, in a deployed state, preferablydefines a multi-tiered arrangement, scaffolding or platform, such as theillustrated coil or helical shape with a plurality of stacked windings,as shown in FIG. 27. The shape of distal end portion of the guide wirein a deployed state may be predetermined. Preferably, at least the coilshaped distal end portion 206 of the guide wire 200 is made of a shapememory material, such as a Nitinol or a polymer having shape memorycharacteristics, so that the guide wire can be deformed into a generallystraight configuration prior to or during deployment of the guide wireinto the treatment site, and then allowed to reform into its initialcoil shape within the treatment site. With this arrangement, the guidewire itself may act as an initial distraction device, contacting theendplates of the vertebra and forcing them apart. For that purpose, theguide wire may also have a cross-sectional shape (e.g., oval) that tendsto reduce contact force with endplates or to keep contact force withinan acceptable range. After the coiled distal end portion 206 of theguide wire has attained the desired positioned within the treatmentsite, the distraction device 202 is inserted onto the proximal endportion 204 of the guide wire followed by a pusher 208. Optionally, thedistal end portion 210 of the distraction device can be tapered, rampedor otherwise configured (as illustrated in FIGS. 27 and 44) tofacilitate insertion and passage of the distraction device through thebone and between the tissue to be distracted.

A small knob 212 can be mounted at the proximal end portion 204 of theguide wire 200 to provide a gripping portion. The knob 212 can be heldwith one hand as the pusher 208 is advanced distally along the guidewire 200, indicated by arrow D in FIG. 28, with the other hand.Advancing the pusher 208 distally forces the distraction device 202 tomove distally, sliding over the guide wire 200. The distraction device202 follows along guide wire 200 into the vertebra and substantiallytakes the shape of the distal end portion of the guide wire to form asupport structure with a multi-tiered arrangement or scaffolding. Forexample, in the illustrated embodiment, the distraction device 202 windsinto a coil shape as it passes over the coil-shaped portion 206 of theguide wire. The distraction device 202 winds upon on itself as manytimes as the number of windings 214 of the guide wire to form amulti-tiered support structure or scaffolding, such as the coil orhelical shaped support structure 216.

FIG. 29 illustrates a completed scaffolding or support structure 216that is defined by the coiled distraction device 202. The extent orheight H₁ of the support structure 216 is determined generally bymultiplying the number of turns or windings by the height H₂ (shown inFIG. 27) of the elongated distraction device. If desired, the guide wire200 can now be removed from the deployed distraction device 202. Theremoval of the guide wire 200 can be accomplished by holding the pusher208 in place while pulling the proximal end 204 of the guide wire 200 ina proximal direction. Optionally, depending on the treatment, the guidewire 200 can remain in place with the distraction device 202 to furtherstrengthen and stabilize the support structure 216 defined ofdistraction device 202. In that usage, the proximal end 204 of the guidewire 200 could be severed from the remainder of the guide wire bycutting, unscrewing or other means as it is known in the art.

It should therefore be apparent from the above that the presentinvention is particularly advantageous and conducive to minimallyinvasive surgical procedures for treatment of the spine. In accordancewith this aspect of the present invention only a single access openingis required, which may be made transcutaneously and through theappropriate spinal bone or other tissue. Through this single opening arelatively large three-dimensional support structure can be built withinthe confined space of an individual vertebra or between adjoiningvertebrae. Insertion of the distraction device may be aided by anintroduction cannula or sheath, or the distraction device itself may bedirectly advanced through an access opening without the need for acannula or other advancing aid. In any event, in the illustratedembodiment a relatively large support structure is built or formed insitu through a relatively much smaller access opening, providing thebenefits of more drastic and invasive surgical approaches with thesafety and ease of minimally invasive techniques.

FIG. 30 through FIG. 35 illustrate the deployment of the distractiondevice 202 into a vertebral body. Referring to FIG. 30, an introducersheath 218 is introduced through the back of a patient while the patientis lying in a prone position. Fluoroscopic guidance using a biplaneimaging system for better visualization of the spine may be used to helpguide the delivery system to the desired location. The introducer sheath218 has a sharp tip to help penetrate the bone structure typicallythrough the pedicle 220 of the vertebral body 222 (in the transpedicularapproach). Once the introducer sheath 218 has passed through or createda passage 219 in the pedicle 220 and is in the desired position, whichcan be confirmed by imaging, a delivery cannula 224 may be inserted intothe introducer sheath 218 and the guide wire 200 is advanced forwardthrough the cannula. Alternatively, the guide wire may be insertedthrough the cannula without an introducer sheath.

As explained above, the guide wire 200 is preferably made of a shapememory material that has an initial or free state in the shape of a coilor spring. As the guide wire 200 is inserted into the cannula 224, thecannula constrains the guide wire into a generally elongated linearconfiguration, allowing an easy and minimally invasive deployment of theguide wire into the treatment site. Because of the shape memoryproperties, the guide wire 200 will return to its coil-shaped free stateonce the constraint is removed, i.e., as the guide wire exits the distalend portion 225 of the cannula 224 and enters the vertebral body 222.The guide wire 200 can be advanced through the cannula 224 manually orwith the aid of an advancing mechanism, such as a ratcheting mechanism,e.g., the ratchet gun shown in FIG. 58.

In order to improve the rate and ease of penetration of the guide wire200 through bone and other tissues, an energy system can be operativelyconnected to the guide wire to transmit energy that enables the tip ofthe wire to drill through the tissue or bone to access the desired siteor obtain the desire configuration. In the illustrated embodiment, theproximal end portion 204 of the guide wire 200 can be coupled to anenergy system, such as a transducer assembly 226 with a piezoelectricelement that produces ultrasonic vibrations at a specific frequency tohelp the guide wire penetrate the bony structure of the vertebral body.Such energy system could include an energy source 228 coupled to thetransducer 226 capable of propagating ultrasonic energy at frequenciessuitable for drilling a pathway into dense material, such as bone. Theuse of such energy systems that may be employed in the present inventionare described in U.S. Pat. No. 6,498,421 to Oh which discloses drilling,U.S. Pat. No. 6,899,715 to Beaty which discloses boring and U.S. Pat.No. 4,838,853 to Parisi which discloses cutting using ultrasonic energy.Such devices have also been used in the vascular system to penetratethrough arterial blood clots as described in U.S. Pat. No. 6,929,632 toNita. All of the aforementioned patents are hereby incorporated hereinby reference.

It will be understood that the energy system as described herein canalso be used in a substantially similar manner to aid in the delivery ofthe above described distraction device 136 of FIG. 12. It will also beunderstood that the use of a transducer assembly is optional and that insome procedures it is advantageous to deploy the guide wire 200 withoutthe aid of a transducer assembly. In those instances in which atransducer assembly is not used, the guide wire can be deployed in amanner generally similar to that previously described above with respectto the deployment of the distraction device 136 of FIG. 12.

As the guide wire 200 exits the distal end portion 225 of the cannula224 and enters the vertebral body 222, the distal end portion 206 of theguide wire begins to return to its unconstrained shape, i.e., the distalend portion of the guide wire begins to wind into its coil shape.Referring to FIG. 31, the guide wire 200 is advanced and deployed intocancellous bone of the vertebral body 222 until the coil shape reachesthe desired height or has the desired number of loops or windings 214.As noted earlier, the guide wire itself may function to distract orseparate the endplates of a damaged vertebra. Preferably, the guide wire200 is advanced until the coiled portion of the guide wire attains aheight that spans the gap between the superior endplate and the inferiorendplate. Further, in certain treatments, as noted above the guide wire200 may itself contact the endplates of the vertebral body and functionto cause distraction of the endplates and enlargement of the verticalheight of the vertebral body, restoring or partially restoring theheight of the vertebra. Alternatively, the coil shaped guide wire may bedeployed within the vertebral body without any distraction or minimaldistraction of the endplates.

Referring to FIG. 32, after the guide wire 200 has achieved a desireddeployed configuration, the introducer sheath and cannula can beretracted and removed from the system and the transducer assembly can bedisconnected. At this stage, the coiled distal end portion 206 of theguide wire 200 is deployed within the vertebral body 222, and theproximal end portion 204 of the guide wire is extending out of thepassageway 219 of the vertebral body. The proximal end portion 204 ofthe guide wire defines an insertion path or track for the distractiondevice 202. Alternatively, when desired, the introducer sheath and/orcannula can be left in place, and the distraction device can be deployedinto the vertebral body through the introducer sheath, the cannula orboth.

One of the advantages of removing the introducer sheath and the cannulafrom the system is that such removal allows for a larger passageway intothe vertebral body. The larger passageway makes it possible to employdistraction devices or implants having larger dimensions. Thus, when theintroducer sheath and cannula are removed, the dimensions of thedistraction device can be larger because the size of the distractiondevice is not constrained or controlled by the size of the introducersheath or cannula. One advantage of employing a larger distractiondevice is that the larger distraction device provides a larger surfacearea that disperses the loading forces acting on the device and resultsin less pressure being placed on any given portion of the device or onthe surface of the vertebral body contacted by the distraction device.

As illustrated in FIG. 32, the distraction device 202 is inserted overthe proximal end portion (not shown) of the guide wire 200, and a pushermember 208 is placed over the guide wire behind or proximal thedistraction device. As the pusher member 208 is advanced, it contactsthe distraction device 202 and advances it forward or distally over theguide wire 200. A ratchet device (shown in FIG. 58) or other advancementmechanism may also be employed to assist in advancing the pusher memberincrementally.

Referring to FIG. 33, as the distraction device 202 is advanced forward(distally) over the guide wire 200, the guide wire guides thedistraction device through the passageway 219 and into vertebral body222. As illustrated in FIGS. 27 and 44 and as noted above, the distalend 210 of the distraction device can be tapered, ramped or otherwiseshaped to aid in passing through tissue.

In the vertebral body, the distraction device 202 follows along thecoiled shaped portion 206 of the guide wire 200 and winds into a coilshaped support structure 216 as shown in FIGS. 34 and 35. The side slotsin the distraction device allow it to bend more easily and follow thecontour of the guide wire. With each formation of an additional coil orwindings 236 of the support structure 216, the support structureincreases in height. As the support structure 216 increases in height,it distracts and supports the endplates of the vertebra, restoring orpartially restoring vertebral height and stabilizing the vertebral body222. When treating a fractured vertebral body, the distraction of theendplates stabilizes the fracture because the load is no longer applyingpressure onto the fractured section or onto the fragmented pieces thatcan pressure the nerve endings surrounding the vertebral body, and thusback pain is reduced.

One advantage of this embodiment of the distraction device, as notedabove, is that it can be inserted through a small access hole and a muchlarger three dimensional support structure, such as a multi-tieredarrangement or scaffolding, can be built within a limited or confinedspace between or within the tissue layers. For instance the distractiondevice 202 can be inserted through a small access hole and the supportstructure 216 can be built one loop at the time by adding one thicknessof the distraction device over another one. As an example, the averagevertebral body is 18 mm in height. As illustrated in FIG. 2, after avertebral body compression fracture, the vertebral body can be abouthalf of the height of a normal vertebral body, which would result in acompressed body of about 9 mm. By way of example, a guide wire in theform a wire with a 1 mm in diameter with a pitch about half of the wiresize would require about 5 loops to span from endplate to endplate. Whenthe distraction device is inserted onto the guide member, it will startwinding along the loops and distract or push up and down in the axialdirection which may benefit from the mechanical advantage of advancingover a coil. Because the fractured body has less resistance, it willexpand the distance between the two endplates until they are preferablyat the pre-fractured position, as illustrated in FIG. 35.

After the distraction device 202 has been deployed, the guide wire 200can be retracted from the distraction device and removed from thesystem. This can be accomplished by holding the pusher member 208 inplace while retracting the guide wire 200 in a proximal direction. Forexample, the guide wire 200 can be retracted proximally by reversing theadvancing mechanism, e.g., the ratchet mechanism of the delivery gun,while keeping the pusher member in place.

The distraction device of the present invention is preferably but notexclusively used with bone filler material to add stability to thedistraction device and support between the distracted tissue, i.e., theendplates of the vertebra. Bone filler may be introduced in a variety ofways. As illustrated in FIG. 36 and FIG. 37, a small tubular element orneedle 238 may be inserted between the windings 236 of the supportstructure or within a center hole of distraction device 202, for examplecentral channel 240 of FIG. 39, so that a bone filler material 242,preferably bone graft material or bone cement, can be injected into theinner area or resident volume 244 defined by the support structure 216.The resident volume 244 may or may not contain cancellous bone. Theneedle 238 could be connected to syringe or other type injection device.In the illustrated embodiment, the distraction device 202 includes slots246 that communicate with the central channel. The slots 246 arearranged so that the slots direct the injected bone filler 242 toresident volume 244 defined by the support structure 216. The supportstructure 216 acts as a barrier that limits and/or directs the movementof the bone filler 242 and substantially prevents the bone filler fromspreading to areas outside of the support structure 216. In other words,the support structure 216 can serve as a containment device thatsurrounds the bone filler 242 and contains it within resident volume 244defined by the support structure 216. The support structure/containmentdevice 216 prevents undesired leakage or extravasation. Preferably, thebone filler 242 is injected until it has completely filled the residentvolume 244 defined by the support structure 216 as illustrated in FIG.38.

FIGS. 38A-38G further illustrate a method of interdigitating a flowablematerial with spinal tissue in accordance with the present subjectmatter. As discussed above, when bone tissue is located in the residentvolume of the structure or barrier defined by the distraction device orelongated member, flowable material, such as flowable bone fillermaterial, can be introduced into the bone tissue located within theresident volume to form a bone tissue/flowable material amalgam, whichprovides strength and support to the bone tissue. As readily understoodby those skilled in the art, the amalgam results from interdigitatingthe flowable material with the bone tissue. Cancellous bone may bedescribed as having a porous sponge-like consistency. Interdigitation isthe flowing of material into and through the pores and interstices ofthe cancellous bone between the trabecula, resulting in a combination ofbone/flowable material structure.

In one embodiment of a method of interdigitation, a working cannula isinserted into a vertebral body through a transpedicular access port. Adeployment cannula is inserted into the working cannula, and a coilshaped guide member is delivered into the vertebral body, in a mannersimilar to that described above with respect to FIGS. 30 and 31.

Turning now to FIG. 38A. FIG. 38A illustrates a top view of a vertebralbody 222 having a working cannula 201 inserted into the vertebral bodythrough a transpedicular access port 203, and a deployment cannula 205situated within working cannula 201. In one embodiment of the method, adistraction device or permanent or temporary spinal implant, such aselongated member 207 is distally advanced along guide member 200 by apusher member 213. Elongated member 207, which may be any suitable shapeor configuration, is advanced along guide member 200, through deploymentcannula 205, out of an opening 209 in a distal end portion 217 of thedeployment cannula, and into cancellous bone tissue 211 of the vertebralbody 222. As illustrated in FIGS. 38A and 38B, opening 209 in distal endportion 217 of deployment cannula 205 is located in the sidewall of thedistal end portion of the deployment cannula.

As elongated member 207 extends out of opening 209 of deployment cannula205 and advances along the distal end portion (not shown) of the guidemember 200, elongated member 207 traverses through cancellous bone 211and defines a perimeter structure or barrier 215, as shown in FIG. 38B.Barrier 215 can, but does not necessarily, distract or support adjacentspinal tissue, such as the endplates of the vertebral body, and may bepermanent or removable. Referring back to FIG. 38A, barrier 215 at leastpartially surrounds or encircles at least a portion 221 of cancellousbone tissue 211. Thus, portion 221 of cancellous bone 211 is locatedwithin or occupies the resident volume of barrier 215. As used hereinthe terms “surround” and “encircle” are not meant to be strictly limitedto the meaning of forming a “circle,” and as such, these terms areintended to include any shape of a barrier that surrounds a portion ofthe spinal tissue.

Turning now to FIG. 38C, after a desired amount of elongated member 207has been deployed into cancellous bone 211, pusher member 213 and guidemember 200 are removed from deployment cannula 205, leaving a proximalend portion 223 of elongated member 207 located within deploymentcannula 205. A guide pin 227 is then inserted through deployment cannula205 and into the opening (best shown as opening 240 g of FIG. 46)located in proximal end portion 223 of elongated member 207. A flowablematerial deployment needle 229 is then advanced along guide pin 227, asshown in FIG. 38D. Deployment needle 229 is advanced along guide pin 227until the distal end portion 231 of the deployment needle enters, meetsor mates with the opening in proximal end portion 223 of elongatedmember 207 in a manner sufficient to allow fluid communicationtherebetween.

After needle 229 is in the desired position, guide pin 227 is removedfrom deployment cannula 205. A flowable material delivery or injectionsystem, such as a syringe (not shown), is operatively connected with aproximal end portion of deployment needle 229 to supply flowablematerial to the deployment needle. Flowable material 233, such asflowable bone filler material, is delivered into at least one fluidpassageway (best shown as 235 in FIG. 38G) of elongated member 207, asillustrated in FIG. 38E. In this embodiment, the fluid passageway is thesame passageway that is employed for advancing the elongated memberalong guide member. In alternative embodiments, the fluid passageway maybe an independent and separate passageway from the one used foradvancement of the elongated member along the guide member.

Flowable material 233 flows from deployment needle 229 and through thefluid passageway of elongated member 207. As flowable material 233 flowsthrough the passageway, the flowable material exits out of slots orapertures 237 spaced along elongated member 207. Flowable material 233exiting slots 237 interdigitates with the portion 221 of the spongy orporous cancellous bone tissue 211 located within the resident volume ofbarrier 215. In other words, flowable material 233 migrates or seepsinto and through the pores or interstices and around the trabeculae ofthe portion 221 of cancellous bone tissue 211 to form a bonetissue/flowable material amalgam. The amount of interdigitation of theflowable material with the bone tissue depends on a variety of factorsincluding, but not limited to, the viscosity and volume of the flowablematerial injected, the rate of injection, the curing rate of the bonefiller material and the amount of injection pressure applied duringinjection of the flowable material. For example, a flowable materialthat is highly fluid and not unduly viscous is believed to interdigitatemore completely with the cancellous bone. Similarly, higher injectionpressure may result in more complete interdigitation, provided that thepressure is not so great as to force a substantial amount of flowablematerial between the windings of the elongated member 207 and outsidethe resident volume, as described below.

As flowable material 233 interdigitates with portion 221 of cancellousbone tissue 211, flowable material 233 is substantially contained withinthe resident volume of the structure or barrier 215 formed by elongatedmember 207. In other words, barrier 215 limits or impedes the flow offlowable material 233 beyond the resident volume and reduces the risk ofextravagation of the flowable material to undesired locations. It isunderstood that the barrier is not required in many circumstances tocontain all of the flowable material, and impeding, restricting orlimiting the escape of flowable material beyond the resident volumeprovides substantial benefits and reduced risks. It is preferred thatabout 90% to 100% of flowable material 233 be contained to withinbarrier 215, although in many applications, it may be sufficient tocontain about 50% or potentially less of flowable material 233 withinthe barrier 215, although it may be preferred that the barrier beconfigured to contain 50% or greater of flowable material.

Referring to FIG. 38F, after the desired amount of flowable material 233has been deployed into the resident volume of barrier 215, and if it isdesired to, deployment cannula 205 may be rotated back and forth withinworking cannula 201 to fracture or separate the proximal end 223 ofelongated member 207, located in the deployment cannula, from theportion of elongated member 207 defining barrier 215 within cancellousbone 211. One of the benefits provided by an ability to fracture theelongated member is that the elongated member can be cut to fit in-situ,which eliminates the need for elongated members of varying lengths.After elongated member 207 has been fractured, working cannula 201 anddeployment cannula 205, containing the fractured proximal end portion223 of elongated member 207, are removed from the vertebral body. Asillustrated in FIG. 38G, after the procedure, vertebral body 222includes barrier 215 surrounding the portion 211 of cancellous bonetissue that has been interdigitated with flowable filler material 233 tocreate a bone tissue/flowable filler material amalgam.

Several significant benefits can be achieved by employing the apparatusand methods described above to interdigitate flowable material with bonetissue. One such benefit is a result of barrier 215 significantlyreducing the risk of undesired extravasation. Because barrier 215 limitsor contains the movement of flowable material 233, the surgeon can useflowable materials with lower viscosities, which, depending on theparticular procedure, may be preferable over flowable materials withhigher viscosities, such as the case of lower injection pressures. Theability to use lower viscosity flowable material allows for lowerinjection pressures, which reduces the need for complex injectionsystems that are typically required for high injection pressures.

Another benefit of the above described method and apparatus is that theelongated member can be used to direct and/or regulate the flow ofmaterial into the tissue of the vertebral body, and more particularly,into the tissue of the resident volume. In other words, the elongatedmember can be used as flow restrictor. As discussed above, the flowablematerial flows through the fluid passageway and apertures, e.g., slots,of the elongated member. The flow rate of the flowable material isaffected by the size of the fluid passageway and apertures, and thus theflow rate can be varied by varying the size of the fluid passageway andthe size of the slots. For example, an elongated member having a fluidpassageway and slots with a reduced size will produce a slower flow rateof flowable material, which may be desirable in certain applications.

The distraction device may have a variety of configurations withoutdeparting from the present disclosure. The different configurationsprovide a variety of advantageous features of the distraction device.One aspect to be considered in regards to an implanted distractiondevice is the ability of the device to resist different forces, such ascompressive and axial forces. It is easily understood that the devicecan resist compressive loading wherein the force on the distractiondevice is axial. However, additional lateral or translation forces canalso act on the device when the body is moving.

FIGS. 39-48 illustrate examples of possible profiles of the distractiondevice and the multi-tiered support structures that can be formed bysuch distraction devices. The various profiles aid in shape retention soas to keep the distraction device in the shape of the deployed supportstructure and substantially accommodate resistance to both compressiveand lateral forces, among other advantageous features. All of theembodiments in these figures preferably include a channel generallydesignated 240-240 i for mounting the distraction device onto the guidewire. The central channel in some embodiments also can be utilized fordirecting the flow of bone filler or the delivery of drugs or otherfluid materials.

In FIG. 39, the cross-sectional profile is generally square and in FIG.40, the cross-sectional profile is generally rectangular. Both of theseembodiments provide windings 236 a and 236 b having substantially flatsurfaces that contact flat surfaces of adjacent windings. The contactbetween the surfaces of each winding provides a support structure, whichis very good at resisting compressive forces. Additionally, asillustrated in FIG. 39 the distraction device can have a porous coating247 throughout or at least on the sides of the distraction device forbetter integration into the tissue to be treated.

In FIG. 41, the cross-sectional shape is a custom tongue and grooveprofile having a corrugated shape with a plurality of peaks 248 andvalleys 250. The peaks 248 and valleys 250 of each winding engage theseof the next adjacent winding to provide interfering surface that addsstability and resists lateral slippage.

In FIG. 42, the cross-sectional shape is a custom profile with a singletongue and groove configuration. The distraction device has a groove 254formed on one surface and a raised rib or tongue 252 formed on theopposite surface so that when wound together the tongue extends into thegroove of an adjacent winding and the groove receives the tongue of anadjacent winding. Again the tongue 252 and groove 254 engage each otherto provide interfering surfaces that add stability and resists slippageand shifting due to lateral forces.

In FIG. 43, the cross-sectional shape is a custom profile having opposedconcave surface 256 and a convex surface 258. When the distractiondevice forms a support structure the concave and convex surfaces 256,258 engage the mating convex or concave surface of adjacent windings toadd stability and reduce slippage and shifting due to lateral forces.

FIGS. 44-48 illustrate embodiments of the distraction device whichinclude features that assist in directing and limiting the directionbone filler injected into the treatment site. In the illustratedembodiments, materials, such as bone filler or medications, can beinjected into one of the channels 240 e-240 i. The material will flowthrough the channel and into slots located in the distraction device.The slots direct and/or limit the flow of the material to a specificregion within the treatment site. The illustrated embodiments alsoinclude features that aid in the insertion of the distraction device andassist in the turning of the distraction device as it is guided over theguide wire. For example, the slots located in the distraction deviceenhances the flexibility of the distraction device, making it easier forthe distraction device to follow the contour of the guide wire.

FIG. 44 illustrates a distraction device wherein the distraction deviceincludes upward directed slots 260. When bone filler is injected intothe channel 240 e, the boner filler flows out of the slots 260 and intoareas on both the inside and outside of the distraction device supportstructure.

In FIG. 45, the distraction device includes outwardly facing slots 260a. When bone filler is injected into the channel 240 f, the bone fillerflows out of the slots 260 a into the area outside of the distractiondevice support structure. Thus, the slots 260 a direct the flow of bonefiller toward the outside of the distraction device, and the distractiondevice support structure acts as a barrier, leaving the inner areadefined by the distraction device substantially free of bone fillermaterial.

In FIG. 46, the distraction device includes inwardly facing slots 260 b.When bone filler is injected into the channel 240 g, the bone fillerflows out of the slots 260 b and into the inner space 244 b defined bythe distraction device. Thus, the slots 260 b direct and limit the flowof bone filler toward the inside of the distraction device, and thedistraction device acts like a container that contains the bone fillerwithin the distraction device, leaving the outside region of thedistraction device substantially free of bone filler material.

In FIG. 47, the distraction device has upwardly and downwardly facingslots 260 c, 260 d, which allows bone filler to flow into regions insideand outside of the distraction device.

In FIG. 48, the distraction device has inwardly and outwardly facingslots 260 e, 260 f. In this embodiment, the inwardly and outwardlyfacing slots 260 e, 260 f direct the bone filler toward both the innerspace defined by the distraction device and the region outside of thedistraction device.

The size and dimension of the distraction device when used for thetreatment of vertebral compression fracture is preferably of a size thatcan be inserted through a cannula no larger that about a 6 gauge size(working diameter about 0.173 inches (about 4.39 mm)) which would allowthe distraction device to have a generally square profile of about 0.118inches×0.118 inches (about 3 mm×3 mm). Other sizes and dimensions couldbe used depending on the application. The length of the distractiondevice could be pre-determined or could be cut to fit during thetreatment.

The construction of the distraction device could be accomplished usingseveral techniques known in the art, including but not limited tomolding, machining or extruding. It is also understood that the deliverycoil or guide member could have different profiles and different shapesaccording to the application requirements.

In one embodiment, referring to FIG. 48 a, the distraction device couldbe comprised of a plurality of individual distraction device elements251, each including a hole 240 j for mounting onto the guide wire 200 afor insertion into the vertebral body. The individual distraction deviceelements 48 a could have a cube-like configuration or could be longer orshorter in length or width depending on the desired use. When individualdistraction device elements 251 are used, the distraction device ispreferably stabilized by leaving the guide wire 200 implanted within thedistraction device or with the aid of cement introduced into the innerarea defined by the distraction device or at least in contact with thespiral or both.

The distraction device also can be constructed by linking a plurality ofindividual distraction device elements together to form a chain-likestructure. For example, a thin section of material could be connected toa plurality of cube-like distraction device elements to retain all ofthe elements together, forming a line or deformable linear structure.The individual distraction device elements can be similarly sized andshaped, or alternatively, each individual element can be a differentsize and shape.

Alternatively, the distraction device can be formed from a bar or rodshaped in which a multitude of slots that can be machined into thestarting bar or rod at regular or random intervals. A channel may bebored through the middle of the distraction device for mounting andsliding onto a guide wire.

The distraction devices and guide wires of the present invention can bedeployed by a variety of different methods and with a variety ofapparatus. It will be understood that the deployment methods andapparatus disclosed in FIGS. 49-58 are examples of what could be used todeliver distraction devices of the type generally disclosed in FIG. 12or guide wires of the type generally disclosed in FIG. 27. Forconvenience, the aforementioned deployment methods and apparatus will bedescribed in relation to the deployment of distraction devices.

The distraction device may be made more effective for certain proceduresby using multiple coil or spring-shaped distraction devices in order tospeed up the procedure and also increase the surface area in contactwith the tissue or endplates in the case of treating vertebras. Incircumstances where smaller distraction devices are used, but thesurgeon desires to have the maximum surface area to support the twoendplates of a vertebra, the surgeon can used a bi-transpedicularapproach for instance as shown in FIG. 49. Two holes are drilled intothe vertebral body 262 and two cannulas 264 a, 264 b can be insertedthrough the holes to deliver each distraction device 266 a, 266 b. Thesurgeon may, preferably, insert one device after the other for ease ofuse and safety concerns. However, at the surgeon's option both could beinserted at the same time. Thus, this invention is not limited to thesequence of insertion.

A double coil or distraction device having a superior device 268 and aninferior device 270 is also shown in FIGS. 50 and 51. Each device windsin the opposite direction, therefore device 268 winds in the upwarddirection and device 270 winds in the downward direction. The devicesare preferably delivered simultaneously but could also be delivered oneat the time. Both devices 268 and 270 wind to the right relative tosurgeon introducing them; however another device could have the devicesthat wind to the left as it might be required. The delivery cannula 272could also have two channels 274 a, 274 b on its distal end to properlyguide each device in its proper orientation. Since the same number ofwinds would be required for a given height dimension, having two devicesbeing deployed at the same time would cut in half the time require todeliver that particular device if only one coil would be used. Thisembodiment is preferably employed when it is possible to access thecenter (height wise) of the vertebral body because the distractiondevice expands in both directions.

Another configuration of a double coil or device design is shown in FIG.52, wherein the distraction device has a first device 275 in an anteriorposition and a second device 276 in a posterior position. The firstdevice 275 winds to the right when deployed and the other device 276winds to the left when deployed. In this embodiment, both of the devices275, 276 wind in the downward direction; however, in another embodimentboth devices could wind in the upward direction. The distal end 277 ofthe cannula 278 has two channels located side by side to properly guidethe devices. In this case, the surface area contact is doubled whichreduces the stress to the tissue or endplate as the case might be.However, the deployment time is similar as to deploying a single coildevice. It might be more advantageous to use this embodiment when onlyone pedicle 279 or one side can be access for a medical or physicalreason, as shown in FIG. 53. This way the surface contact area issignificantly increased.

In order to both reduce delivery time and double the surface contactarea, another distraction device configuration is illustrated with fourdistraction devices in FIG. 54. Basically, it is a combination of thetwo previously described devices. The two devices 280 and 281 arelocated in a superior position and side-by-side, with device 280 windingto the right and device 281 winding to the left. Both devices also windin the upward direction. The other two devices 282 and 283 are locatedin an inferior position and both are winding downwardly with device 282winding to the left and device 283 winding to the right. This design ofcourse, potentially requires a larger cannula 284 to accommodate thefour different materials for each of the distraction devices.

In addition to a manual pushrod advance of the distraction device,semi-automated or automated apparatus may be provided for ease of use.FIG. 55 shows a schematic representation of an automatic design using acannula 285 for the delivery of the distraction device within the bodyto the treatment site. The apparatus has a set of motorized rollers 286to push out the distraction device 287 in its un-deformed configurationfrom a holding cartridge 288. The controls of such an apparatus wouldinclude stop and start commands and potentially a reverse command sothat the distraction device can be retrieved. It could also includeindication of delivery speed and force resistance encountered by theadvancing distraction device into the intended tissue in question.Additional features could be added to such apparatus as it is well knowin the art.

FIG. 56 shows the coil distraction device 287 being delivered and as therollers 286 spin in the direction represented by arrow E and F, thefriction exercises onto the distraction device will make it move intothe direction shown by arrow G.

Another device and method to deliver the distraction device areillustrated in FIG. 57 as a semi-automated type of device with manualcontrol of the delivery action. The distraction device 287 a is mountedon a rotating spool which is connected to a handle 289, and carried witha housing 290. The distraction device extends through a fixed cannula291. By turning the handle 289 in the direction indicated by arrow, thedistraction device is fed along the cannula 291 until it exits at thedistal end and takes its un-deformed state at the treatment site.

FIG. 58 illustrates a ratchet feed device 292 that preferably has anadvancing mode and a retracting mode. In the advancing mode, uponactivation of the trigger 293, the distraction device 294 advancesincrementally through the cannula 295. In the illustrated embodiment,the trigger 293 is activated by repeatedly squeezing and releasing thetrigger.

FIG. 58A illustrates another embodiment of a ratchet feed device 292 ain which the distraction device or guide track exits out of the side ofthe distal end 297 a of the cannula 295 a.

As noted above, the present invention relates to devices and methods totreat a condition that requires skin, tissue, organ, bone or acombination of those to be distracted from one another and supportedapart of each other, either on a permanent situation or a temporarysituation. It is also more specifically applicable for the treatment ofvertebral compression fractures. The distraction device is alsoparticularly well suited for the treatment of intervertebral disktreatments and spinal fusion.

FIG. 59 illustrates a section of a vertebral (spinal) column 300 havingadjacent vertebrae 301 and 301 a and an intervertebral disk 302 locatedbetween the vertebrae 301, 301 a. A disk nucleus removal tool 304, suchas rongeurs, curettes, probes and dissectors, is shown accessing thedisk 302 via a posterior approach. As illustrated in FIG. 61, theremoval tool 304 can be inserted through a small access hole 310 in theanulus fibrous 312 to remove the disk nucleus pulpous 306 usingtechniques and procedures generally known to those skilled in the art.

Referring to FIG. 62, an open space or disk nucleus space 308 is createdby the removal of the disk nucleus 306. Additionally, the small accesshole 310 that was created in the disk annulus 312 during the nucleusremoval can be used to access the disk nucleus space.

In one preferred method of delivering a distraction device in accordancewith the present invention, referring to FIGS. 63 and 63A, a deliverycannula 314 is inserted through the access hole 310 and a guide wire 316is deployed into the nucleus space 308 through the cannula 314, usingsimilar procedures and techniques as described above. Similar to theembodiments described above, the guide wire 316 has an elongated linearconfiguration for delivery through the cannula and a coiled or deployedconfiguration upon exiting the cannula. After the guide wire 316 hasbeen deployed, the delivery cannula 314 can be retracted and removedfrom the delivery system. A coiled portion 317 of the guide wire 316 isleft occupying at least a portion of the nucleus space 308, as shown inFIG. 64, and a proximal end 318 of the guide wire extends from the disk302 to define an insertion path for deployment of a distraction device.

As illustrated in FIGS. 65 and 65A, an implant or distraction device 320is advanced distally over the guide wire 316. The distraction device 320can be advanced over the guide wire 316 with the assistance of a pusher319 or an advancing mechanism, such as the delivery ratcheting gun 292of FIG. 58, or by any other suitable method. As the distraction device320 advances over the guide wire 316, the guide wire guides thedistraction device into the nucleus space 308. The distraction device320 follows along the guide wire 316 and winds into a coil to form asupport structure 313 substantially similar to the support structures ofthe previous embodiments.

Once the distraction device has achieved the desired deployment, thedelivery wire 316 can be removed leaving the support structure 313 inplace as shown in FIG. 66. Alternatively, the delivery wire 316 may besevered and left within the distraction device 320. In addition to thedistraction device 320, bone filler, such as bone cement or cancellousbone graft material, may be inserted around the distraction device topromoted bone fusion. The complete fusion process is expected to requireabout 6 months to be totally healed. If required, supplemental fixationmay be added to the spine to prevent instability during the healingprocess.

An alternate deployment method in accordance with the present inventionis illustrated in FIGS. 67-71. FIG. 67 illustrates an intervertebraldisk in which the nucleus has already been removed. A guide wire 322 a,similar to the guide wires described above, is deployed through acannula 314 a into the nucleus space 308 a in a generally similar manneras described above. After the guide wire 322 a has been deployed, ifdesired, the cannula 314 a can be removed from the system. The coiledconfiguration of this embodiment of the guide wire has a tighter wind(smaller diameter coil), and thus occupies only a portion of the nucleusspace 308 a.

As illustrated in FIG. 68, a distraction device 324 a is placed over theguide wire 322 a and deployed into the nucleus space 308 a, in a similarmanner as previously disclosed. The distraction device 324 a followsalong the coiled guide wire 322 a and winds into a coil to form asupport structure 313 a as shown in FIG. 69. Because the wind of thecoiled guide wire is tighter, the cross-sectional width “J” of thesupport structure 313 a is smaller than in the previously describedembodiment, and thus the support structure only occupies a portion ofthe nucleus space 308. After the distraction device 324 a has beendeployed, the guide wire 322 d can be removed. Alternatively, the guidewire 322 a can be severed and left within the distraction device 324 a.

After the distraction device 324 a has formed the support structure 313a, if there are excess portions of the distraction device, the excessportion may be severed and removed. In other words, the distractiondevice can be cut to length after deployment. One of the advantages ofbeing able to cut the distraction device to length is that a singledistraction device is capable of being deployed over guide wires ofdifferent radii, lengths and coil or deployment configurations.

As shown in FIG. 69, a second guide wire 322 b is deployed through acannula 314 b into the nucleus space 308 a adjacent to support structure313 a. A second distraction device 324 b is then deployed over the guidewire 322 b, as shown in FIG. 70.

FIG. 71 illustrates an intervertebral disk after the two distractionsdevices support structures 313 a, 313 b have been deployed within thenucleus space 308 a. One advantage of employing two distraction devicesis an increased surface area occupied by the distraction devices, whichprovides for aided support and distribution of forces.

The previous methods have been described for a posterior access to thespine. However, in some situations, especially in the lumbar region, ananterior approach is desired. FIG. 60 illustrates an example of ananterior approach. In such an approach, an incision is made in the bellyof the patient and the main organs such as the descending colon 330,aorta 332 and inferior vena cava 334 are dissected and pushed to theside and then held by retractors 336 to provide an access to thevertebral column 300. One advantage of this approach is the ability toaccess the disk space from the anterior and complete a fusion when theend plates 338, 340 of adjacent vertebra are not parallel, as shown inFIG. 72, but have a wedge like shape making is difficult to insert adistraction device from the posterior approach.

In the situation where the end plates of the adjacent vertebra are notparallel it may be preferable to use a distraction device that forms asupport structure having oblique ends. FIG. 74 shows one embodiment of asupport structure 341 formed by a distraction device. The supportstructure 341 has a top portion 342 and a bottom portion 344 that aregenerally angled toward each other. The support structure has ananterior portion 346 and a posterior portion 348. Preferably, theanterior portion 346 is taller than the posterior portion 348,conforming the support structure to the wedge-like shape between thenon-parallel vertebral plates 338, 340 as illustrated in FIG. 72B.

One advantage of an oblique configuration is that it can be used with aposterior approach as illustrated in FIG. 72A, which is much lessinvasive than the anterior approach just described. The posteriorapproach allows for a faster recovery period without sacrificing thewedge type implant desired for these particular cases.

The distraction device having an oblique configuration can be formedfrom the distraction device ribbon 349 as illustrated in FIG. 73. Thedistraction device ribbon 349 has a pre-deployed state having peaks 350and valleys 351. Each peak 350 is spaced apart by a defined pitch “P.”The peaks 350 and valleys 351 of the distraction device 349 are spacedapart so that when an appropriate guide wire is employed, thedistraction device forms the support structure 341 of FIG. 73 having alonger anterior dimension. Such a support structure can be achieved bydeploying distraction device 349 on a corresponding guide wire that hasa coiled configuration having a radius that matches the appropriatepitch spacing.

FIGS. 75 and 76 illustrate another embodiment of the present inventionwherein the deployed configuration of the guide wire 352 would have asingle layer spiral portion 353. As illustrated in FIG. 76, the guidewire 352 is deployed through a cannula 355 into the open space 308 bcreated by the removal of the disk nucleus. As the guide wire 352 exitsthe cannula 355, the spiral portion 353 of the guide wire forms withinthe nucleus space 308 b. Referring to FIG. 77, the distraction device354 is inserted over the guide wire 352 and advanced into the nucleusspace 308 using methods and techniques generally similar to thosepreviously described. The distraction device 354 follows along the guidewire 352 to create a single layered generally spiraled support structure356. Optionally, the delivery track 352 can be removed leaving behind awell compact distraction device. FIG. 78 illustrates the distractiondevice support device 356 deployed in this spiral configuration. Anadvantage of this embodiment is to provide for a single layer of thedistraction device occupying a wide area and to provide good support andstability for fusion.

The distraction devices of the present invention can also be used fortotal or partial vertebral body replacements (VBR). In one minimallyinvasive partial VBR procedure of the present invention, an endoscopicprocedure, generally similar to the procedure described above withrespect to FIG. 26G, can be used to remove damaged vertebral bodytissue. This procedure can include inserting a vertebral bone removaltool through a small access hole of the vertebral body to remove damagedportions of vertebral bone. After the damaged bone has been removed, adelivery cannula 400 can be inserted through an access hole 402,typically the same access hole created for bone removal, in vertebra403, and a guide wire 404 is deployed into the vertebral body 406through the cannula, as illustrated in FIG. 79.

As the guide wire 404 exits the distal end portion 408 of the cannula400 and enters the vertebral body 406, the distal end portion 410 of theguide wire begins to return to its unconstrained coiled shape. The guidewire 404 is advanced and deployed into the vertebral body until the coilshape reaches a desired height or has the desired number of windings412.

After the guide wire 404 has achieved a desire deployment configuration,optionally, the cannula 400 can be retracted and removed from thesystem. At this stage, the coiled distal end portion 410 of the guidewire 404 is deployed within the vertebral body 406, and the proximal endportion 414 of the guide wire is extending out of the passageway 408.The proximal end portion 414 of the guide wire defines an insertion pathfor the distraction device 416, as illustrated in FIG. 80.

The distraction device 416 is inserted over the proximal end portion 414of the guide wire 404, and a pusher member 418 is placed over the guidewire behind or proximal the distraction device. As the pusher member 418is advanced, it contacts the distraction device 416 and advances itforward or distally over the guide wire 404.

In the vertebral body, the distraction device 416 follows along thecoiled shaped portion 410 of the guide wire 404 and winds into a coilshaped support structure 420. With each formation of an additional coilor winding 422 of the support structure 420, the support structureincreases in height or extent. As the support structure 420 increases inheight, it distracts and supports the endplates 424, 426 of thevertebra, restoring or partially restoring vertebral height andstabilizing the vertebral body 406.

After the distraction device 416 has been deployed, the guide wire 404can be retracted from the distraction device and removed from thesystem. Alternatively, the guide wire 404 could be severed and leftwithin the distraction device 416. Optionally, bone filler such as bonecement, allograph or autograph, or therapeutic drugs may be inserted inor around the device, by similar methods described above, in orderstabilize the device and/or to promote bone fusion.

In one minimally invasive method of a total VBR procedure, the vertebralbody removal tool described above can be used to remove substantiallyall of the vertebral body of a vertebra 401, and a disk removal tool canused to substantially remove the adjacent disks. Referring to FIG. 82,the distal end portion 408 a of the cannula 400 a can be inserted intothe space 430 created by the removal of the vertebral body and adjacentdisk, and a guide wire 404 a can be deployed into said space, usingsimilar procedures and techniques as described above. As the guide wire404 a exits the distal end portion 408 a of the cannula 400 a, thedistal end portion 410 a of the guide wire 404 a begins to return to itsunconstrained coiled shape. The guide wire 404 a is advanced anddeployed into the space 430 created by the vertebral body and diskremoval until the coil shape reaches the desired height or has thedesired number of loops or windings 412 a.

After the guide wire 404 a has achieved a desired deploymentconfiguration, the cannula 400 a can be retracted and removed from thesystem. Referring to FIG. 83, the distraction device 416 a is insertedover the proximal end portion 414 a of the guide wire 404 a, and apusher member 418 a is placed over the guide wire behind the proximalend portion of distraction device. As the pusher member 418 a isadvanced, it contacts the distraction device 416 a and advances itforward or distally over the guide wire 404 a. As the distraction device416 a is advanced over the guide wire 404 a, the guide wire guides thedistraction device into the space 430 created by the removal of thevertebral body and adjacent disks. As the distraction device 416 afollows along the coiled shaped portion 410 a of the guide wire 404 a,it winds into a coiled shape support structure 420 a. With eachformation of the additional coil or winding 422 a of the supportstructure 420 a, the support structure increases in height. As thesupport structure 420 a increases in height, it distracts and supportsan endplate 432 of a superior vertebra 434 and an endplate 436 of aninferior vertebra 438, as shown in FIG. 84.

After the distraction device has been deployed, optionally, bone filler,such as bone cement, allograph or autograph, or therapeutic drugs may beinserted in or around the support structure to stabilize the supportstructure and/or to promote bone fusion.

Although the present invention is described in light of the illustratedembodiments, it is understood that this for the purposes illustrationand not limitation. Other applications, modifications or use of thesupport or distraction device may be made without departing for thescope of this invention, as set forth in the claims now or hereafterfiled.

What is claimed is:
 1. A method of interdigitating bone cement withnative cancellous bone tissue of a vertebral body comprising an outercortical wall and native cancellous bone therewithin, the methodcomprising: forming a barrier circumferentially surrounding the nativecancellous bone tissue of such vertebral body; and interdigitating bonecement with the native cancellous bone tissue surrounded by the barrier,the barrier substantially preventing flow of bone cement from thesurrounded native cancellous bone.
 2. The method of claim 1 includingforming the barrier from an elongated member.
 3. The method of claim 1including forming the barrier by inserting an elongated member into thenative cancellous bone tissue and forming the elongated member into anarcuate shape to define the barrier.
 4. The method of claim 1 in whichthe interdigitating includes delivering bone cement through at least aportion of the barrier and into the native cancellous bone tissuesurrounded by the barrier.
 5. The method of claim 4 in which thedelivering includes directing the bone cement from the barrier towardthe native cancellous bone tissue surrounded by the barrier.
 6. Themethod of claim 5 further including controlling the flow of the bonecement through the barrier and into the native cancellous bone tissue.7. The method of claim 1 wherein the barrier comprises an elongatedmember extending in a generally helical shape within the vertebral bodyand circumferentially surrounding native cancellous bone.
 8. A method oftreating a vertebral body having a superior endplate, an inferiorendplate and native cancellous bone tissue therebetween, the methodcomprising: inserting a generally elongated member into the nativecancellous bone tissue of such vertebral body; changing theconfiguration of the elongated member within the native cancellous bonetissue to form a generally cylindrical structure extending around anaxis that intersects the superior and inferior endplates, the generallycylindrical structure at least partially surrounding a portion of thenative cancellous bone tissue; and introducing bone cement into theportion of the native cancellous bone tissue surrounded by the generallycylindrical structure to interdigitate the bone cement with the portionof native cancellous bone tissue.
 9. The method of claim 8 in which thegenerally elongated member has at least one fluid passageway, and theintroducing includes introducing the bone cement into a portion of thenative cancellous bone tissue through the fluid passageway.
 10. Themethod of claim 9 further including controlling the flow of bone cementthrough the elongated member and into the portion of native cancellousbone tissue.
 11. The method of claim 8 in which the generallycylindrical structure comprises the elongated member extending in agenerally helical shape within the vertebral body and circumferentiallysurrounding native cancellous bone.
 12. The method of claim 8 includingchanging the shape of the elongated member so that the structure formedsubstantially completely encircles the portion of native cancellous bonetissue.
 13. A method of treating spinal bone tissue, comprising:advancing an elongated member into native cancellous bone tissue of avertebral body, the elongated member having at least one fluidpassageway; forming the elongated member into a curved configuration asthe elongated member is advanced into the native cancellous bone tissue,the curved configuration defining a structure within the vertebral bodythat at least partially surrounds a portion of the native cancellousbone tissue; and flowing bone cement through the at least one fluidpassageway of the elongated member into the portion of the nativecancellous bone tissue surrounded by the structure.
 14. The method ofclaim 13 including wherein the advancing includes guiding the elongatemember along a guide member into the native cancellous bone tissue. 15.The method of claim 14 wherein the guide member includes an arcuateportion, and the elongated member is advanced into the arcuateconfiguration by advancing the elongated member along the guide member.16. The method of claim 13 further including controlling the flow of thebone cement through the elongated member and into the native cancellousbone tissue.
 17. The method of claim 13 wherein the curved configurationcomprises the elongated member extending in a generally helical shapewithin the vertebral body and circumferentially surrounding nativecancellous bone.
 18. A method of treating a vertebral body, having outercortical bone, inner native cancellous bone, a superior endplate and aninferior endplate, the method comprising: inserting a barrier having afirst configuration for insertion into a vertebral body that containsnative cancellous bone tissue; changing the configuration of the barrierso as to form within the vertebral body a second configuration thatsurrounds a generally inner region of native cancellous bone tissue, thesecond configuration substantially prevents the flow of bone cement fromthe generally inner region of native cancellous bone in one or moreselected outward directions toward the cortical bone; injecting flowablebone cement into the generally inner region of native cancellous bonetissue so as to cause interdigitation of bone cement and nativecancellous bone tissue; and the barrier substantially preventing theflow of the bone cement in the selected directions within the vertebralbody.
 19. The method of claim 18 wherein the barrier, in the secondconfiguration, extends in a generally helical shape within the vertebralbody and circumferentially surrounds native cancellous bone.